please explain more. I am not doubting you, but I thought the double barreled shotgun was very reliable?
They most certainly can be; HOWEVER, a SxS that is well built is the most labor intensive gun to make - whether rifle or shotgun. Hence, they tend to cost a LOT more than similar guns that are O/U, pumps or semis which can be easily cranked out on CNC equipment. Quality SxS guns are meant mostly, for fast-handling bird-hunting situations so their barrels, balance, triggers, etc., are all hand done.
Cheap SxS, in order to make a certain price point (and O/U or other for that matter) scrimp and cut corners on every quality aspect they can and still make a gun that goes bang (most of the time). However, their longevity is not certain, therefore their reliability is also suspect. ANY gun can fail early on, but cheap guns (and cheap is NOT the same as inexpensive), will fail more often than a quality built gun.
Example: Michael McIntosh, a noted gun writer, extolled the virtues and longevity of his AyA #2 SxS, stating he had over 120,000 rounds through the gun with no issues. Currently these guns start about $5500. AyA makes a few other models that are less, typically the cheapest is the 4/53 which starts at $3400. The point is this - these guns are meant to be shot a lot in the field and used on fast-moving birds - something they were designed for. These really aren't beginner's guns, but they are the beginning price point for quality.
Stoeger, Yildiz, Baikal, Stevens, etc. are not built to the same quality level (why they don't cost near as much), and while some here will espouse about their "ruggedness, built like a tank" or some other supposedly good feature, the reality is they can't build a quality gun at their price point. This means that reliabilty, longevity, etc. are not typically present. Now if you want one of those for some fun, backyard pest control, informal targets and you don't shoot a lot, they'll probably do fine, because when they break, it shouldn't be at a critical moment - but if you are relying on one of those for competition where the money is on the line or HD where your life is on the line, I would suggest something different