Quotation marks may break scripts because they are used to insert (except) special characters, etc.
If you try, for example, to use make a regex filter in the options, and there is some sort of punctuation mark in the text you want to filter, it won't work.
That's why spammers and shills have all kinds of crazy punctuation in their posts. Harder to filter. You have to find a unique piece of text with no punctuation marks in it to get the regex to stick.