Time to get on my high horse: people shouldn't be able to sell their IP any more than they can sell themselves into slavery. It's not okay to scam people just because they signed a contract allowing it.

Any contracts that allow a company to profit from an IP without compensating the creator should be considered void immediately.

In any case, remember to never give up ownership of ANYTHING you create. Always create a limited non-transferable license to use it. If a publisher refuses to sign such a contract, walk.