What to look for in a used lens?

I wanted to pick up a used lens. What should i look for?

Check for dust and mold on the inside. Dust and light scratches shouldn't effect pic quality, but I wouldn't want them on my lens. Check the contacts to be on good condition. Check the filter thread to make sure they arnt stripped....Hmmm that's all I can think of.

well the seller is 8 hrs away by car. he had reliable feedback and he said it is in perfect condition so i believed him.
i got a 50 1.4 with hood for 280 bucks shipped.

You asked what to look for, so I told you.

Well that's almost new price. I would have got the new one with the 1 year warranty.

thanks for the input.
what should i look for when testing this lens?