#1
How long should a nut last assuming its a cheap plastic type one that would be on a 300 dollar guitar. I use nut lube but when i change my strings lately the nut slots are dirty like worn off metal and my tuning stability has been taking a small turn for the worse lately. I do a good amount of bending and my guitar is 6 months old (played every day). Could it be worn out and if it is would a brass nut last longer if i replaced it with one? How much might that cost to have done?
#3
nut lube, hahaha, i lol'd...

the nut could last an incredibly long time, it all depends how you treat it.
#4
you should be able to hit people in the face with your nut and it should be fine, a plastic nuts pretty cheap though