Stay the course. CPS and guardians ad litem have a bad rep, here, too. It's a circular problem. The judge appoints a guardian. She may or may not be fair. The parent or parents may complain to the judge, but few judges will admit to a mistake or poor judgement.
I rented to a non-custodial parent this summer. Kids doing okay with his relatives, and oddly, in the end the powers that be decided his alcoholic wife should have primary custody. He just takes them as often as he can and documents the times wife is too busy, has commitments, etc. Here's the kicker: she's completing a program for addicts/alkies. Her boyfriend is an alcoholic that isn't allowed to be around the kids. (but who wants to give up a boyfriend, right?) So he can't stay with her, or be around the kids. Good news is that by this fall, CPS is out of the picture. It's now up to the two of them and their lawyers to decide visitations .
And yes, to add to the chaos, they have an open marriage, which is why I encouraged him to move along. Having the kids hear their parents talk about dates with other people was more than I wanted to know.