1. Recaptcha. I think every faucet user experienced problems with it, I don't think that I need to repeat what was already said
2. Coinhive miner. I hate it, especially when faucet owners don't give any warning about running miner script in background.
3. In general, claiming from faucets become much more difficult and there is too much hassle to get few satoshi. Close popups, solve captcha, antibots, then view url shortener and you need to close popups, solve captcha and after everything you get 5 Satoshi. But it's reality, faucet owners have to monetize website somehow, it's not that easy, and they can't pay big rewards due to big price of btc.
Sometimes I'm missing times when it was possible to claim only after solving easy captcha, faucets were paying 500-1000 satoshi :/ . On the other hand, we should enjoy that bitcoin rised so much since then.
These are very nasty points. Personally, I'm not bored with the rewards amount, I'm fine with this, what disturbs a lot is the difficult to claim from a simple faucet. Overloaded pages with several ads, captchas, pop-ups, lagging short-links... If it were easy to claim, we could make profit from the quantity of pages we visit, but as it takes a lot of time to claim 20 satoshis from a faucet, people are going away and stop using faucets... Impossible to use many faucets as we need to waste a lot of time at few of them.
Would be nice if there were a system like FreeBitco.in, where you could deposit satoshis, so the site would let you use the faucet without the need of solving captchas. Like a faucet network for trusted people that won't cheat it. It would save a lot of time...