I've used several cheap scopes and have had decent luck with them. I don't think they are nearly as bad as many guys online make them out to be. I will also say that 98% of the guys I hunt with use scopes under $150, and most of those are well under $100. I had to go up to $150 because a couple of them use higher powered Simmons scopes that cost right over $100, but most of them were in the $30-70 range. It's very rare that any of them have a problem, and most of them kill plenty of deer year after year with them.
I will include a few stories of cheap scopes that I've had. I bought most of them in my younger days, or got them thrown in with something I purchased. I buy decent optics most of the time now, but with most of them it's not a huge difference that I see between the two, just that I get more piece of mind.
I will also mention that I killed a pretty decent 8 point buck with a $30 Tasco Bucksight 3-9x40 mounted on a muzzle loader several years ago. Then I also killed my biggest buck, with the same muzzle loader with the same $30 scope. It wasn't a world class buck by any means, just large for this area. It was made in China, and purchased at Walmart for $30. The glass in it is pretty decent, the scopes has held zero, and overall I'm pretty impressed by it. I've also been out in rough weather quite a bit and it's never fogged up on me. I'm very impressed when you consider the price. I bought a second one of these to use for 2 months while my Leupold was sent in for repair, and this one worked just as well for me. When I got my Leupold back, I sold this Tasco to a buddy and he is still using it to this day as am I with the one my muzzle loader. They are about 4 years old. I have thought about changing this out, but I just can't bring myself to do it as long as it keeps working well.
A friend has a similar but not exactly the same model Tasco's on a rifle that I've shot quite a bit also. The glass on this one isn't nearly as good as the above two, but it's still decent and clear enough for any hunting scenario in legal light around here. It stays zero from year to year, and has been pretty decent as well.
The other cheap scope I still have is a Simmons Deerfield 3-9x32 that is also made in China. I purchased this one about 7 years ago. It's only mounted on a .22, but it's been dropped, thrown around, bounced around in the truck, and generally just had a hard life. It's always held zero, it has pretty good glass. Even better than the Tasco. For reference, It's got better glass than both the Leupold VX-I and Nikon Prostaff I used, but isn't quite up to par with the Burris FFII. It tracks well, and it just overall works great. It's also never fogged up on me. If I'd known how well this scope was going to hold up I'd have bought 10 of these.
I had another Simmons that was a Blazer 3-9x40 that would be about 3 years old now that I got on a rifle I bought. The previous owner had used it for a year and was pretty rough on it. I used it for 9-10 months and it never moved the POI on me, and it had surprisingly good glass too. The only complaint I had about this one is the tracking was absolutely horrible. Each click was more like 1" at 100 yards instead of 1/4". However, once you got it sighted in, it stayed sighted in and worked pretty well. I'd have no qualms about using this on a hunting rifle. That said, I ended up selling it to a friend that wanted a scope, and I upgraded.
I had a Bushnell that came used on a .22 also, and this is the only cheaper Bushnell I've had. It's the one that comes on several of the Savage package rifles now. I can't say I want another one. This was one of the sorriest cheap scopes I've used. The glass while clear enough to use, sucked. The edges of the glass looked like looking through plastic, but it was decently clear in the center. The adjustments were absolutely horrible. If you made adjustments it would take a few shots to settle in, or you could tap on the top of the scope to get them to settle in. Either way it was a pain. I'd thought people tapping on their scopes were crazy as I'd never done this, and didn't want to abuse my scope, but you had to do it on this one. However, once zeroed it did hold zero. It just didn't impress me at all. I'm sure you could have taken it out and killed a deer with it, but overall, I thought it sucked, and I ended up selling it.
I also tried one of the Center Point 4-16x40's and I liked it as well. It replaced the above mentioned Bushnell. The only reason I don't still have it is because when I sold the rifle, the buyer wanted the scope also and paid $60 extra over my asking price for just the gun. Knowing I could buy another one of these new for $70 and not having anything else to put this one on I let this one go. It didn't have great glass, but was useable. At the higher powers it looked like it had a slight smoke screen to it or something. Just looked washed out, but was useable. At lower powers it was pretty decent. This one also never lost zero on me, and to my surprise it tracked perfectly and was always repeatable. The turrets on this one really surprised me. I'd have no problems using one of these either. This one was also made in China.
Last but not least, a Simmons 8 Point 3-9x40. This is the only one that has failed on me out of all of the ones I've used. I bought a Leupold scope from a guy and he threw this one in for free. He said it was new, but I can't confirm that. It looked new and didn't have any ring marks or anything, but at the same time he didn't have the box, and said one or two other things I found out weren't true later on so I'm just not sure if this one was new or use. I mounted it on a very hard kicking 30-06. I went to sight it in, and on shot number 6, something that looked like a paint chip or something started floating around inside of it blocking part of your view. This is the only cheap scope I've ever had break on me.
Considering the luck I've had with most of them, and the luck most of my friends have had with them, I just find it hard to believe that they are as bad as they have a reputation for online. I bet between the group of guys I hunt with there are probably at least 50 of these cheap scopes being used if not more than that.
Now would I take one of these on a African Safari, or a trip that cost me thousands? Not only no, but heck no. I'd want more piece of mind that I got with a cheap scope. However, would I take them hunting on an average hunt? I sure would. Heck, I even drive 2.5 hours to hunt, and I'd take them to hunt in a situation like that.
I will also mention that I've used several Bushnell products, a few Elite series scopes, a range finder, and some other accessories in addition to that cheap scope. Every Bushnell product I've used, while working, has left me disappointed. So I tend to shy away from Bushnell. Unfortunately Bushnell now also owns Simmons and Tasco. I've been fairly happy with the Tascos which I think were made after Bushnell owned them, but with the two Simmons, one of them failed, and the other one while decent tracked horribly. A lot of the guys I hunt with with Simmons, own ones that are pre Bushnell also, so I can't comment on the ones that have been made since Bushnell took over other than the couple I've used other than one buddy that bought a new Aetec and the adjustments were backwards on. That said a few guys I hunt with do use Bushnells and have had okay luck.
This is just my personal opinion on them, and review of the scopes I've used for anyone interested.