you're smushing two different concepts together again!
the band may need to look professional and appropriate, that's a no-brainer.
as long as the amps at a wedding or something aren't covered in duct tape, stickers and spray-painted graffiti, nobody cares what they look like (except if they're too big, then they might look "too loud" for a nervous event planner).
Hey, where can I get some of those dummy Marshall stacks like the real professionals use? I need a few of those for my next gig at Starbucks.
I do get beans-on-toast's point. Disney, Carnival and the Borg will probably care how your gear looks. It's like "jeans day" at a cubicle job. The workers get so excited. But you can't just wear any jeans, you have to spend good money on a pair of company-approved Dad jeans. Between the Dad jeans by day and the professional looking cabs by night, I can't afford my mortgage -- and my cab still doesn't match my head.
All joking aside, I'd really like to imagine that I don't care about looking the part. But I'll be darned if I didn't pass on cabs that come with Peavey logos because they don't look professional. I'm too bald to think like this, but that's how it is. I know I'm not the only one. The first thing people want to do when they get an awesome new Squier is to put a professional looking Fender sticker on it. A lot of people don't give in to that temptation, but they're definitely fighting it. Brand consciousness runs deep, and it's a form of mental slavery.