In our case DS2 and his friend X are both 5. X has mum who suffers from depression and phobias, dad who's just had to leave the home under restraining order after hitting mum and sister while drunk, two lovely teenage sisters that do a lot of the parenting, one of whom is suffering from depression, and two other brothers aged 6 and 3. All the children attend school daily in a scruffy but accurate version of school uniform.
The teachers are very positive about the friendship saying it has been really good for my DS2 - that he and X have both had their developmental problems but when they get together they "complete" each other. Which is a lovely thing to hear and makes me feel grateful and loyal to X's family. I'm also a bleeding heart liberal so think it's bad for everyone if my son's friend's family are treated as pariahs (which they are) on our playground. Plus in my family growing up we had two things going on - undiagnosed mental illness and occasional violence. So those things are not outside my experience (though the drink, suspected drug use and poverty/poor money management are).
But the teachers caution me against sending DS2 to X's house because it is too "chaotic". If I bring X and sometimes his brother to our house on a playdate, I get comments from teachers the next day like "have you been babysitting again?". It's as if they struggle to believe I'd actually want to be friendly with this mum. So that's weird. They've referred the family to social services.
Other teacher friends have told me "not to get involved".
But my instinct is that the best thing for my son is for me to treat the mother with respect. The mother and daughter both seem to be opening up to me a bit more - sharing stories about the latest social services report and whether the father should be able to see the little ones. My feeling is that it's safer for my child if I am "involved" to this extent because then I know the real story, rather than just responding to various vague descriptions like "chaotic". One thing that helps a lot is that they are not needy. They never ask me for anything - no requests for favours, etc.
Obviously it would be a lot more convenient if his friend came from a stable background but hey ho - there's nothing I can do about that.