(Remind me to write a bloggish tirade later about why commas are important and necessary, will you?)
Add a comma after head (long introductory phrase). Add another comma after beings (dependent clause).
Delete these before horrifying. (If you leave these in place, it suggests you mean this kind of horrifying beings as opposed to some other horrifying beings.)
Unless you mean to imply most people are all sharing a single mask, change mask to masks.
Don’t hyphenate town hobo.
Use a comma, not a colon, before dialogue that follows a tag. Change the colon after asks to a comma. (Whether it’s in a dialogue tag or not, you shouldn’t use a colon after a verb.)
Add a comma before too. (Yes, this matters. That comma makes the difference between too meaning excessive and too meaning also.)
After hitting your head, you’ve seen most people as horrifying and ugly beings, as if they had suddenly lost their masks.
The crazy town hobo notices you gawking one day and asks, “Wait, you can see them, too?”
(I’m here to chew bubblegum and not-so-silently correct grammar… 🙂 )