If I was going out for a posh dinner, I'd dress appropriately. If I was going out for fish and chips, I wouldn't care what I was wearing.
Besides the point I think but I wouldn't go to a party in a house that required payment for entry whether it was 20 quid or 200 quid.
If I was going to a ball, I'd dress appropriately in a nice evening dress. If I was going to a rave I'd dress appropriately in jeans and comfy shoes.
Don't we all adjust to our surroundings so that we fit in as well as we can?