Do you realise when your main melody/harmonies are off or is your brain just physically (or cognitively) unable to do so? 

also known as: 

Collabing discourse 

Back in the day I always volunteer to do the harmonies for all the collabs I was in. High low highhigh lowlow doubles bgvs everything, you name it. 

BUT NOOOOT ANYMORE. 

Unless i'm the mixer of the collab, I will never do a full set of harmonies. Maybe only high, or only low. Unless i was personally asked by the host, I will never do a full harmony set for a collab. 

Because why bother. 

My hard work gets inexplicably tainted when: 

1. It was put on top of off-tune main parts. which makes everything sounds off, including my otherwise innocent harmonies. 

2. It's used by very mindful mixers who don't bother to exercise some common sense and not dump everyone's parts together regardless of whether they're on pitch or not.
As a mixer, you have the freedom to edit. EDIT. Use that advantage and maybe, probably, if someone's harmonies are off, or flat,  or just plain wrong, don't include it in the final mix! 
Be ruthless and cut off people's messy harmonies. Just delete the layer. Poof. Gone. Easy. Your need to please everyone will never help you in producing a good collab. 

I'm so pissed if I've done my fair share of harmonies (which are most of the time correct, thankyou very much. If you want proof, well there's many and you should know better than to clock me.) and when I listen to the end result, it got butchered because the mixer decided to put someone else's off harmonies on top of mine. 

Yay. 

And that's why I'm asking, 

Can you hear them? Or do you really think those off notes are not off? 

I'm curious. 

ps: yes this confirms that if there are off harmonies in collabs that I mix, 
I cut them. 

Most of the time. 

If i couldn't be bothered to do so i will just leave them be. 
Most of the time i couldn't be bothered so, 
it.