I have also used a number of different knives over the years with all types of locking mechanisms. There are a few things to be aware of with liner locks.
The test referred to above by stoven is a good one. Holding the handle with the blade facing up, bang the back of the blade against the palm of your hand to see if the liner lock will disengage. Also, inspect the position of the liner lock to see how it lines up on the butt of the blade when engaged. The entire thickness of the liner (or 90% of it or so) must be behind the blade. If a little bit of the liner does not quite make it to support the blade, be careful as it can slip off under pressure. Although, as the liner lock wears in, it will move over. If it is too far over when new (if it is all the way over to the other side of the blade or makes contact with the opposing liner), the piece must be rejected. But particularly critical, in my opinion, is how exposed the liner lock is to your index finger when griping the handle. Some liner locks are buried down into the handle. This is best, even though it can be a bit difficult to disengage as you have to dig down to reach the liner. But if the liner lock is raised or otherwise exposed, then you can inadvertently apply pressure to the lock when using the knife. This has happened to me with several knives, even though they were high quality.