I know when I'm recording a band, I usually tell them up front what I'll be doing:
I'm not here to judge their music. If they want my opinion on something, I'll give it, but they must understand it's only my opinion. If I hear something I don't think is working, I'll point out why I think it's not working, and I'll offer some suggestions on how it might work better. But then, it's their job to evaluate my statements and either change it if they agree, or tell me that's what they want, in which case, it's my job to make it work.
I do consider myself an extra set of ears, but I'm really just a casual observer, with no standing in the band. If I hear something that I don't think the band is aware of, I'll point it out, but it has to be their call about what to do about it.
My job is to help them get what they're paying for - a good recording of their music. If they ask for help, I'll give it to them, with the understanding that they must make the final decisions as to whether my suggestions are of any use to them.
Some people call that production; I don't.
In the end, it's their name that goes on the front of the album, not mine.