You're right about that, they aren't that known in the west... I've got a feeling that their 'destination' was generally Asia, they are very famous in Thailand, Philippines, China of course and so on...
Yes, I've read they were terribly mistreated, I've also read that for ex. Wu Y!f4n was abused (while practising I think) and other members (mentioned that Korean ones) did nothing. Of course there's possibility that they actually couldn't do anything but still it is sad... :/ And of course in kp0p foreign members are treated harsher. There was also a conflict between him and Ta0... It is so strange that they were falling apart practically at the beginning.
I agree that bt5' performances are not really spectacular, though I have to admit that the first thing that caught my attention was their choreography. But meh... Sorry for saying that, but right now I'm so sick of them...
Good that you pointed it out, I mean debut song... Actually it was really late that I found it and this mv is sooo creepy...
All those symbols are awful, but as you said about their music, they have good vocalists (unlike bt5, I don't mean to offend, just not in my taste