What's the definition of 'taking advantage' or 'exploiting'? If that's 'business', can we assume that some people just don't play along these 'business rules'?

What's the definition of 'taking advantage' or 'exploiting'? If that's 'business', can we assume that some people just don't play along these 'business rules'? Arguments like these are the reason that I've a hard time getting along with the sales/marketing (and sometimes management) people around me.