My 2000 blue golf had the timing belt "changed recently" when I bought it. No paper work, no proof. Popped the covers when I got it home at 149k miles and Oh my....I really wondered if it had ever been changed. Intake clogged to a dime sized hole too. Lots of work ahead of me, but she turned out to be a really nice car.
Bought a 2001 bug in 2012 with 56k miles. Had a new IP just installed and timing belt kit by Chaplin's Bellevue VW. I inspected it when I got home and yup, everything looked new. Invoice parts listed were all correct and complete. They darn near stripped the water pump bolts by over tightening them as I discovered at the next change. I took the dealer installed TB to 100k miles.
Bought a 2002 bug also with recent timing belt changed. No paper work, no proof. Got home and inspected. Timing belt looked like it was recently changed, but the water pump and other bearings clearly not.
Bottom line, as others have said, unless you have proof, or know the seller or guru that did the work and can verify, err on the side of caution and proceed as if the timing belt is now due to be changed.