Correct, one is (superficially) regarding their appearance and one is regarding there opinions. There is no decision on which one of the two is correct for forming an opinion of someone else, whether negative or positive.

(note. I added "superficially" in brackets after writing the above because I realised you can correctly make reasonable assumptions (% plays, not 100% correct) based on appearances eg. fat people are lazy, and do not take pride in themselves. Assuming oriental poker players are more likely to be gamblers is not wrong.)

It would definitely depend on why you hated them and whether the correlation was strong. eg If you said:

"I hate xxxx because they are closed minded and gullible."

If you fill in "blacks" I would consider that unreasonable, but if you fill in "Christians" I wouldnt be concerned.