Hey UGers

I'd like to know what things I should be wary of in second hand effect pedals and how I may be able to identify any problems with them. I'd appreciate it so much if you would leave a quick comment.

Thank you!
Does it work ? How am I going to power this? Name brand is easier to resell.
Fender Mustang/Derfenstein DST> Boss Power Wah> Pedal Monsters Klone> Bogner Uberschall> Walrus Audio Janus> Randall RM20> Line 6 M9> Randall RM20
check the switch to make sure it goes on and off easily with no pops or clicks. check the knobs to be sure they all work properly without crackles. the input and output jacks should work properly. the effect itself works in all settings. dings etc are more of a personal thing if you can live with them then no biggie if not then check for that kind of thing.