Profitable if you're lucky and have time to constantly check on altcoins... It's a bit like normal mining, there's risk involved, proportional to how much you go in.
But your paying a premium for rentals. Normally it is cheaper to own the gear and mine yourself assuming right conditions.
Since this is in the bitcoin area not sure how much altcoins have to do with OP. That would be scrypt and a copletly different type of mining. It sounded like OP is talking about BTC mining.
And i you are mining BTC with rental you pay premium. Only way you are not is if you are renting to solo mine hoping to get lucky. But your talking about a lot of cost and risk.