Yeah those sound like faucets which give you a very small amount of BTC.  Unless you have a ton of referrals it doesn't make sense since you might earn a few dollars over several months.

Personally, I'm on one PTC (Pay to click) site and make a few dollars of BTC a month with over 700 referrals so this is a really inefficient way to earn BTC. 

As some other people have said the best way to earn BTC is to either sell your services or do signature campaigns which is more difficult up front but provides a greater chance of a larger payout.