any lock can fail. go with quality and you will probly never have an issue. buy a $20 lock back made in tiawan and you will PROBLY be having issues. the key term is ALWAYS: QUALITY.
material
maker
dealer
all should be of QUALITY. look at price second to quality.
I recently picked up a Kershaw Vapor 3. It's an all stainless body frame lock with a 3.5" blade and a very smooth action. It was around $25.00, and I'm very pleased with it. After bad experiences with liner locks on a Schrade that I used to carry, I tend to avoid them.
i carry a spyderco tenacious. i reversed the belt clip and cut out the thumb hole so when i pull it out it opens as well from the pocket.. the holes on the knife allow you to postiion the clip for left or right handers. there service is good too. lost a screw cause i didnt lock tite it i sent them an emai regarding info for a replacement and 24hrs latter they asked what i needed and where to ship...and they mailed me 3 screws and sent me a 2011 catalog and price list for free. i thought that was pretty cool.