Dress code in New Zealand bars?

depends on the bar itself. most would accept tidy casual . some wont accept sneakers, hoodies or caps

No black jeans in most Wellington bars

Just by some black t-shirts and pants and look like you are depressed and say negative stuff about Aussies and I guarantee most Kiwis wound accept you.

I don't think you would be inconspicuous in a 3 piece suit and black shoes. I would just wear clean casual clothes without lewd messages printed on them, good shoes/sneakers and just behave yourself, that's more important than clothes.After all there may be other people in the bar who just want a quiet time.

The dress codes really vary, but to be safe, I'd say a shirt with a collar, jeans that aren't ripped, and shoes other than sneakers would get you in everywhere you want to go, and also not look too overdressed or out of place. Hats or jandals (flip flops) probably aren't ok if you're going out at night. Maybe if you're hanging out at a bar having a drink during the day. Even in small towns some of the nicer bars have dress codes. The last town I was in didn't let guys into some bars if they were wearing any kind of sneakers or t shirts.

It depends on the bar; most bars and nightclubs in the South Island don't have one and what you described would be perfectly normal and you'd get looked at oddly if you walked in wearing expensive Italian designer clothes. I'll let Aucklanders and Wellingtonians speak for their cities though.

Casual tidy. for example jeans and t-shirt Some places don't allow singlet times (even disigner singlets!!!) Someplaces don't allow hats. Depends where you go.