They are worthless other than keeping small kids from doing something bad.
If the lock secures the gun TO something, then yes, otherwise, not so much.
I have a huge gripe with trigger locks, (and internal locks) on guns. I'm not at all against the idea of securing the gun, and making it safe, I just hate the idea, pushed by so many, that putting a lock on a loaded gun is a good idea. IT IS NOT! (in my opinion).
And I find the idea of putting a lock on an unloaded gun (to make it "safe") to be foolish. UNLOADED, there is no danger. Lock the gun IN something, or TO something, unloaded, its as safe as safe gets. Lock the ammo in something else, and you add another layer of protection.
Put a trigger lock on a loaded gun, and you are running a risk I find unacceptable. The only thing that belongs on a trigger is your finger, at the moment of firing.