For the mean words: It's because she's rejected from their society. Social isolation hurts different.
For the dirty dress: Same reason above, plus most probably her dress worth more than her yearly income. Some may also give emotional meaning to the dress, like memento from her mother or...
I mean remedy for smallpox is quite well-known. Meanwhile the technicality of the procedure itself is left to the populace that has been doing it for years.
I mean quite early it's been established when he fought Drake that comparatively his fighting skill was amateurish, he's only strong because of his level and class.
And all of the people he fought in the recent chapters has higher level than him.