I've been running a faucet for sometime. Yes it can be profitable but you have to be very careful managing how much you give out and your expenses.  To put it short My faucet expenses per month usually run about $1,500 that's buying coins hosting ect. Most of the time the ad revenue covers this expense and leaves a little extra. Sometimes it does not I had 4 months this year where it was in the red. I've never paid for advertising or even created a banner getting traffic to a faucet to me was not difficult but it could be for new sites.  If you are going to run one do it right have a top level domain don't break your publisher terms of service because that's the easiest way of dropping any revenue from your faucet. Rewards have to be high enough to keep users interested but low enough to cover those few who spam the faucet all day every day.  I personally wrote a script that checks the bitcoin & altcoin prices to adjust with my set daily budget. Prior to that I was manually adjusting which required me to check in on the site 6 hours or so. I wouldn't suggest running only 1 coin as you will only get X amount of hits and most of them will be repeat traffic (not worth as much for must publishing networks). Stay away from popups they can be enticing because they usually offer a pretty high cpm but you end up losing your viewers.  Finally you have to be prepared for low CPM countries such as Russia, Ukraine, and Brazil being the main source of traffic.  Try to make the site easy enough for these countries either by directly translating or keeping the layout simple so they can easily navigate.