yes and NO
if you can find unmolested atv's in all stock condition, I say YES, they can be a good starting point,
BUT finding all stock used atv's is rare!
so, on that side of things NO
HOW an atv was used is a HUGE part of its wear and tear factor and or possible bigger problems down the road
BIG tires, snorkels and such, are all things MOST one's never designed there atv's to use
never mind those that think atv's are boats(not bashing here)
pulling tractor like implement for hrs is another thing they were never designed for, yet very common use for them
an atv is NOT a tractor , like it or not, two totally different animals!
every used atv needs to be based on location and condition period IMO
no set rules work really, just starting points MAYBE!