Here is my personal experience with the fringes of this issue over a lifetime of watching it play out before my eyes... If a female is attracted to the guy, things he says or does are considered "cute", "flirtatious", and/or "interesting". If not, the same actions are often considered "creepy", "jerkish", and yes even "sexist". I think its just human nature to perceive things in this way, and since women grow up in s…
Yes, someone not attractive is more likely to be considered creepy - but that's correlation, not causation. Being creepy is extremely unattractive!
An example, which is by no means an outlier: A friend of mine met a man. The man is very attractive, in the particular way that the woman in this story likes, and they had some key common interests. She was extremely attracted to him in short order.
Then he did something creepy. Bam, not attractive anymore. There was no immunity conferred by the other attractive qualities - being creepy was unattractive enough that he was no longer considered attractive.
It is a rather sad fact that many... "socially less capable" people can be a bit oblivious of how their actions seem to other people, and the dividing line between flirty and creepy. Without the necessary skills to tell the difference, it does appear that this distinction is arbitrary, or predicated on other variables (e.g. visual attractiveness).