Differences in NEW servos

For anyone who has dealt with lots of servos...

So I bought 12 NEW Tower Pro sg90 servos off Amazon, made a quadroped and wrote some code to make it stand up.

I noticed 2 strange things... First, at least one motor had a grossly different range. I was able to fix this problem by adding 400 to "max" on servo.attach().

Second, a different motor has completely crap torque. It can't lift up its corner (the lightest) of the robot.

I know Tower Pro isn't the greatest name but are these sorts of issues considered normal in new servos? Experiences?

Bonus question: Is there some resource out there to find info about servos before I buy? I.E. (idle current, stall current, torque, etc) I tried to research a couple servos before buying but info was really spotty/anecdotal.

tia, Michael

HobbyKing seem to have some data on the servos they sell from what I've seen. If you buy cheap/unbranded you are more likely to have issues like this.