Buying a bike -- importance of age vs. mileage

[tractorman]

Hello. Noobie here. I am thinking about purchasing a used GZ250 -- I'm 55, took the MSF safety course 9 years ago, and rode all of 10 miles on a bike that was too powerful and heavy for me and scared me. Never got on it again. I sat on a GZ250 and it seemed comfortable and fit me ergonomically.

I searched the forums and did not find my question discussed, although I may have missed it. Sorry if I did.

My question is this: Ideally it would be nice to buy a newer bike (say 2006 and newer) with low miles (say under 5000 miles.) But if you had the chance to buy an older bike, say 2000, with low miles, or a newer bike with 12-14,000 miles, for similar money, and they both look really good, how would you decide? I'm thinking about internal stuff you cannot see. Are there certain rubber or plastic parts (seals, tubing, air intake parts, etc.) that deteriorate with age and need replacing on an older bike regardless of how few miles it might have? How about those 10-year-old tires? (I know some people that say on a car, don't use a tire that old no matter how good the tread.) Assuming the newer bike has good tires, will the higher mileage make any difference?

I know when I buy used cars from a private owner I try to get a sense of how responsible they appear to be in terms of maintenance, etc., and place some importance on that. But buying from a dealer doesn't give you any sense of previous owners.

Your thoughts would be appreciated. Thanks.

Mark