Pippen, let me tell you a story...
Like you, I tend to take in waifs and strays. This hasn't always been beneficial for me, let me tell ya!
Several years ago when I first moved to Tasmania, I helped out a friend - he'd lost his home (share house, other person moved overseas). He needed somewhere to crash, so he stayed with me. No probs, it was nice to have someone there (I'd just ended a longterm relationship and was feeling the end of the world and the echoes of lonely rooms). Roomie ended up moving interstate for a job.
A year or so later, he's back in Tassie. No job now. He came to stay with me. He wasn't paying board or anything. Then he borrowed money. Then more money. I'd not long bought a new car, so I let him use the old one. Then the parking tickets (in my name) started coming in. So they all got returned with stat decs (because I sure as heck hadn't got the tickets!). I eventually signed over the old car to him - his tickets, his problem.
Then he started working cash jobs at a pub in the city, about 40 minutes away from home. He'd drink, so he'd end up crashed out in the car overnight, or find some random to crash with. He was home less and less. Never paid me back any of the money he owed. And still the parking tickets kept arriving in the mail, along with older tickets that had gone through the court system, and then the summonses started.
Meanwhile Roomie, presumably now ex-Roomie, just didn't start coming home at all. Next I see on FB he's moved 2 hours away to live with his elderly parents. And yeah I still have some of his stuff here in my home. Last time I saw Roomie (oops, ex-Roomie) was September last year. And STILL the tickets, summonses etc arrive in the mail. I now have a canvas tote bag stuffed with them - I don't have an address to send them. And that's not counting the ones that got returned to sender.
October last year another Friend moved down from Queensland to live with me (different bedroom to ex-Roomie). Friend is at home one day when the police turn up, looking for ex-Roomie. No she says, she's never met him and she's been here since October. No problem, the cops leave a card. I call them back and speak to them, tell them what's happened. All seems fine, however summonses etc continue to arrive.
Three days ago I see on FB that ex-Roomie's elderly parents are packing it in and moving to a retirement village, which means ex-Roomie is now, once more, looking for a place to hang his shorts. And yesterday, once more, Friend had a visit from the police looking for him. They wanted to speak to me, I told them the story again, hopefully this time my home will not be listed as ex-Roomie's home any more and we will be left in peace. I suspect not, but I can always hope.
Now, ex-Roomie hasn't asked if he can come back here. I would hope he realises that with the drama I've had that I will not be welcoming. But if he does ask, the answer will be a resounding no. No, no, no. I shouldn't need to provide a reason, he knows what he's done. Whilst I have sympathy for anyone in his situation, it doesn't mean that I need to lay down and act the doormat and provide for them. His problems are 99.9% self inflicted, and it isn't my job to fix them for him.
Now, virtual cookies timtams if you got through that!
Pippen, your moocher friend knows why you don't want her back, she just doesn't care. It sounds like my ex-Roomie and your moocher friend have a lot in common. Just tell her no when she asks. She really doesn't need a reason, she knows the reason. And you know what? You don't need a reason either. It is YOUR house, hun. It is your decision who you live with. If she can't respect that, she isn't a friend and doesn't deserve your headspace.
Good luck! Pity there's no exterminator company that deals with persistent moocher problems, they'd have a great business!