I've heard some of these before, and others are just straight racist or stupidity, not ignorance.
A project by Harvard students to bring comments and questions that they find offensive to themselves, their races, or backgrounds. Worth reading because, even if you disagree, it's still important to know that what you say can offend, and perhaps it will make you think twice, have better relationships, and enjoy more open dialogue for change.
I noticed, for example, that one girl seemed offended that someone would say "I don't see color." I never would have thought this would be offensive. I think it was probably intended to be accepting of race as simply an attribute (much like blonde hair or green eyes) as opposed to the all-encompassing characteristics of a person. But now that I know this, I will be more careful with my speech, or perhaps have a dialogue with others about how they would take this information (taking care not to expect one person to speak for an entire race, obviously, as we are all unique individuals with different histories and opinions shaped by our environments).
The more you know, the better the world will be...educate yourselves.
Be quick in thought but slow to speak.
Do not be afraid to correct yourself when you find fault.