Posted By:
LetsGoBucsIn terms of stamps I agree with the previous post about stamps.
There are issues. Re-gumming was a problem in the 70's, but its pretty easy to spot. There have been attempts at forgeries. There have been alterations being done and not mentioned. But there is a stamp association that has done a lot to handle and shed light on these problems.
I'm not involved in stamps really anymore and I do know that now things are being graded just like in baseball cards. We'll see what kind of effect that has. Most collectors would use the associations authentication services but there previously wasn't the 10, 9, 8 type grading being done.
I'd say that the stamp market is somewhat similar to the art market - its international in scope and has been around for a long long time.
My own opinion is that the stamp market is "cleaner" than the art market or the baseball card market. I can't really comment on coins.