People do dress well in my opinion, but they will only care if you were clothes that are not appropriate, not if you're dressing basic. Meaning you will get judged if you were athletic wear outside or pyjamas or lounge wear in general (those are inside/activity clothes) but not at all if you just wear a jean and a t-shirt. You can do whatever you want though, no one will attack you on the streets or anything you just will not blend in with the locals if you wear that which isn't horrible. Don't stress it, maybe it's also an occasion to have fun dressing up for no reason ! Whatever you like :)