is this discrimination, sexism or stupidity?

thefourthvine wrote about being a female trying to by comic books.

i was saddened and disgusted by her treatment at several comic book stores.

The first time I tried to go into a comic book store without my boyfriend, I discovered that I had a superpower in the comic book world. I was invisible. I could not get anyone to acknowledge that I existed. There were guys behind the counter, yes, but they kept up their argument about Green Lantern while I stood in front of them. I had to interrupt, finally, to ask my question, and then I discovered my second superpower: I had a wall of silence surrounding me. They exchanged glances, gestured vaguely to the back of the store, and went right back to their argument. I left without finding the book I'd come for, but that's just as well; I don't think, based on future experiences, I could have gotten them to take my money if I'd found it.

I thought it was just that comic book store. Then I thought it was just that one and the next one, the one where I discovered that I could not force my money into the hands of the guy behind the counter; he walked away from the register when I approached with books in hand, then disappeared into the back of the store for, apparently, eternity. It was crazy; it was like I'd gone back in time a hundred years, and they still had Wolverine everywhere.

before you say "well not every comic book store is like that." the comments prove it.

i was never really into comic books. the one time i went into a comic book/collectables place with my brother the guy behind the counter barely looked up from his paper. it never occurred to me (or my brother i bet) that it might have been because i was female. we just thought the guy was a jerk.

now i know there are some guys who have trouble talking to women, or anyone really. however, i've been in places where the clerk barely looked at any of the customers, but was happy to take their money.