My boyfriend has shitty friends. What to do.

He is 33. His friends are 27-38. Half of them have drive and a concept of responsibility. No one is perfect, but at least they are trying to help themselves. Some of them are doing very well.

The other half are users. The occasional FB comment here or there makes them feel like they can call him up to ask for money and/or a free place to stay (we are one of the few friends with a house but no kids). We don't have money to support anyone or feed another mouth. They don't call just to say hey. They don't ask how he is doing. They get themselves stuck in these ruts of bouncing from one couch or cheap room to the next. A lot of these people are really smart but love booze and are too lazy to try to find (and keep) a job that pays more than $7.25 an hour.

Now, I don't really mind hanging out with these people when we are in town (these are hometown friends), and I don't think he needs to end his friendships, but at what point do you point out that some of these people are blatantly using him and exploiting his good nature?

He got so worried over his friend not having a place to stay that he wanted them to stay with us. For free. With no money in their pocket or job prospects (or skills). Unfortunately we can't afford to house, bathe, and feed another adult (AND their dog). He quickly understood this when I explained it to him, but he maintains that this person is a good friend. Honestly, this person isn't even trustworthy enough that I would feel comfortable having them in my house when I am away. This friend is never there for him when he needs money, or a place to stay when he's in town, or even as a shoulder to lean on. They don't answer his calls when they don't need him. This is once specific friend now, but there are at least a dozen people who randomly call us when they need something but don't extend any other form of friendship.

So, question is, how do I say this to him? I had these types of friends before but I knew to keep them at arms length and not get emotionally invested in the holes they dug themselves into. Maybe I'm young and I don't get it, but when I help my friends out they always have my back when I need it. Because that's what friends are for, right?