Are looks deceiving?

Yes they are. I have fallen into the trap of forming an opinion about someone based on what they look like. Usually this opinion was stinkingly wrong. (I was young and most things were based on what people dressed like as I was always in St.Vinnies specials and had a huge chip on my shoulder.)
Ít is a reflex that we develop that is really required by our psyche - it is a bit of a safety device. If people look "good" to us, that means we will be safe around them. If they look "bad" to us then we are threatened and feel unsafe, they may harm us.Our subconscious is sending us a warning to be careful.
So it is a reflexive and defensive mechanism, but then we are always told to "get to know someone".
Sometimes getting to know certain people allows them in and then it can be difficult to disconnect.
It is therefore important to know if our reactions are based on ego cues ( she is too fat, too beautiful, too rich ) or intuitive cues ( something about him just does not feel right, something she says does not fit with how she acts ect..)
It is important to read the signs and energy people send out, maybe one day it could save you from a really sticky situation.It does not mean that you are aloof or critical, it just means that you are being careful and those people worth knowing will understand.