I'm not saying you shouldn't say excuse me when you do certain things, I mean, it's just polite you know? And I do want you White People to be polite.
But being polite and tripping over your White Privilge are two different things.
Polite is saying gazoontite after someone sneezes. Polite is saying "No Comment" after someone asks you about those alleged photos of your genitals instead of something crass like "WTF are you asking me that for you dumbmuther fucker. Do those look like the balls of Brett Favre? Do you think Brett Favre would have his naked little linebackers photographed anywhere except Glamour Shots? And who the fuck are you anyway?"
What's not polite is when you say "Excuse me" but what you really mean is "I don't care if you were standing there already looking at the HDSLR's because I'm an old White Guy with my daughter who asks questions like 'Why would anyone want to have to manual focus anything?' -- so we take precedence over you."
See, that's not polite (and probably not money well spent either btw).
But I think you may have picked up on that when I didn't actually excuse myself from the space that I was in and continued to look at the camera that I was going to buy - because honestly -- I'm just not as polite as you are.