The concept Ola explained makes sense I think - enable spellchecking globally for certain widgets, e.g. textareas only, and disable it on case to case basis, assuming that most textareas are supposed to be filled with text that makes sense to spellcheck, whereas there are few textareas that are an exception to that and they would be easy to tag with :nospell.
I usually switch the spell checking feature off because I don't want to bother with setting it up correctly and I believe those who need it can as well activate spell checking on their browsers, but that's easy to do with the current parameter set up.
