What goes around comes along - at least I believe that.
My conscious doesn't allow me to rip someone off. I have been asked the value of stuff and told them, its worth this $$$ but I'd pay $$$ and sometimes got it and sometimes didn't.
I think helping is very important in our lives. Ripping off someone isn't my sort of thing, but i've met many folks who act like they have 'gotten' over on someone. No thanks.
When I see Bob selling his dads guns, I cringe a bit, but not everything is important to them as you and me. I always just shake my head, but for all I know, they kept the coin collection or kept his (or her) car.