I think anyone that has been in karting long enough will eventually deal with those same issues. I have bent all of the above mentioned items, and still have a perfectly working, trouble free kart. That does not say however that bending such items will never cause further issue.
Whether a kart has been damaged or not, it is a risk you take anytime you buy a used piece of racing equipment. You’re pretty much as the sellers mercy and it all comes down to how honest or “up front” the guy is going to be. There are a few checks you can make to the chassis to see if it’s in the ball park or “normal”. But in general, I don’t think a previouisly “bent” part immediately indicates a tweaked chassis (it could, but not always 50/50).
As far as “not handling right” – that’s funny, I hear the same thing from alot of guys driving “show room fresh” karts. That’s a vauge statement. In your case with the “load of spares”, you might just have to consider worst case scenarios. Worst case being needing a new chassis. It is a buyers market!!
I know – you read all that and you’re still left with the same questions!!??
We may not be the fastest on the track...but we're having the most fun!