Disallowing certain characters just gets my goat. I purchased a new WiFi extender last week, went to install it, and it is incapable of utilizing the password on the main router because it contains "special characters". In other words, they wanted me to use an alpha-numeric password. Fuck that - I'm not compromising my password because some "circle C" wrote your code - back to Amazon it went.
Comes back to one of my sayings: "How do you write code like this?" Jeez, its just a fucking string, its actually harder to exclude characters than it is to just swallow the whole thing.