There is no danger in providing your Bitcoin address.
For sites that use inputs.io, certainly you have to provide some way for them to know which account to credit. The security of that account depends on the strength of your password, and how much you trust inputs.io.
A more fundamental problem with these faucets is that they are a complete waste of time. The ones I've seen offer .00001 BTC for looking at an ad, solving a captcha, and entering your account info. This takes 30 to 60 seconds. At current exchange rates that is roughly 10 US cents per hour, about 2 percent of minimum wage, for perhaps the most boring work I can imagine.
It's also not a good way to just pick up a few satoshis to start playing with the system, because thanks to aggregators like inputs.io, you typically cannot get your coins until you have earned BTC .0005 or so, which would take about an hour. Totally not worth it.
In short, I think if it were a scam, they should be offering much better bait.