I guess I am alone then, I DON'T do T-perms to test a cube. In fact I don't just blindly do any type of perms, what I usually do is do a 2gen scramble and solve, which tests out tension, friction, corner cutting, and so on, all at once. It's also a good test of how good a cube is for F2L, which is much more important to me than being able to do specific permutations fast. For bigcubes the first thing I go for is <Rw,U> fingertricks.
I think the T-perm thing ties into one thing I think is really annoying: when I give someone a cube to try and say it's "delicate", and then they pop it within three seconds. I always tell them that it is their responsibility to find the pieces, clean them off, and put it back together. Stop doing T perms, guys. I'm completely serious. If you do your fastest algorithm, all you're going to identify is cubes that fit what you're expecting when you do that algorithm, rather than cubes you can do good F2L (or whatever) on. And if the cube is a bit loose or you have to be careful with it, all you're going to end up doing is locking up and having a pop, and (in case you couldn't tell) the person who owns the cube usually does NOT appreciate that. Believe it or not, some cubes are good for things other than corner cutting at 10+ TPM.