If the child is wearing protective head phones and is out of harms way, I think it is the BEST form of parenting. You are teaching your child from a young age to be tolerant of different people, that tattoos, piercings, weird hair are ok to have. You are bringing them into the best kind of world that speaks/ shows your child that they can be themselves and there is a place for them. 

I mean there are certain situations where you have to be a parent, if you see a person smoking weed in the venue (and you don’t want your kid around that) you have 2 options, tell security or leave. If you live in a state where you can smoke cigs inside a venue, don’t put your child in that environment. 

Just my opinion.