I've operated a fairly large hosting company for the past 5 years, and can tell you first-hand, we generally don't care.
There is one thing to look for however, a line in just about every shared hosting company's TOS - and that is this: they reserve the right to give you notice to leave if you eat up a certain % of system resources. This can be a bit obscure, since if you get large enough, sooner or later it's just plain going to cost them more than $5/month to host you.
That said, if you're successful, sooner or later you'll end up in dedicated hosting, which is really better anyway (more control for you, you know the resources that you have, and it's generally much simpler to come by as many IP's as you want).