As someone looking forward to taking part in bounty campaigns, I've been wondering how easy it is to exchange altcoins.

Would it be true to say that all ERC20-based coins can be freely exchanged to ETH?

This is my main concern at this point, I wouldn't like to be paid in something I'll have to sit on for months, before it appears on exchange(s).

Pardon my noobie Q! Thx