It's only bad manners if the term used is deemed to be offensive. Personal is ok, but not something that might upset someone if you drew attention to it.
Fat - not ok to comment on because it's not seen to be "acceptable" in our culture and it's not polite to draw attention. It's also fairly subjective so open to interpretation and offense.
Red head - fine and inoffensive. Factual
Big nose - not ok because it is factual yet also personal. Not really seen as socially desirable characteristic I should know, I have one but I don't want someone pointing it out thanks
Glasses - ok, factual and socially acceptable.
Black - ok, factual and socially acceptable.
Indian - ok (unless the person is not Indian), factual and socially acceptable to be Indian.
Tanned - ok if the person is tanned. Not ok if the person is non-white and therefore not tanned but is brown or black.
Tall - fine and sociall acceptable.
Blonde - fine and socially acceptable.
Curly hair - fine and socially acceptable.
Afro - fine (unless it's not an Afro) and socially acceptable.
Ugly - not ok, it's subjective and personal.