Not every crypto faucet site are scam, although there are very many low quality sites that end up being time wasters. What to know is scam sites promise great returns in exchange for a little work you do. A reliable faucets will show you clear payout policies, zero hidden taxes and they always have a very good reputation in the cryptocurrency community. Before using any faucet sites, carry out your own research properly.
I think many shady faucets exist, which is why some people call them scams, but it's not fair to put every faucet into that category. On the other hand, the scammers tend to lure the users with unrealistic promises. At the same time, there are some good genuine faucets where you actually get what they promise.
True, faucets are not scams, but often are just misunderstood. I always tell newbies to do their research by checking some reviews or payment proof before investing their time. If the faucet has a popular online presence , it should be more trustworthy.