February 5th, 2012.
Today, I learned I was previously spelling Brussels sprout(s) incorrectly. I was not aware of the ending s on Brussels, nor was I aware of the capitalization.
Singular: Brussels sprout.
Plural: Brussels sprouts.
When used at the beginning of a sentence: Brussels sprouts are extremely trick in nomenclature.
When used in the middle of a sentence: My taste buds were seduced by those amazing Brussels sprouts.
I apologize for my poor English.

It took me a few months to figure this out… My auto-correct kept using that annoying red dashed line if I spelled it “brussel sprouts,” but I didn’t realize why!
Usually when I write, It’s in a text editor, so I actually don’t have spell check until I make it a draft or paste it into a Word document. That being said, I don’t even think my spell check ever underlined it. Then again, I use Linux, so that might be the root of the problem. Glad to hear I’m not alone!
It seems to depend on what text-writing program I use. Microsoft Word often catches it, as do particular internet programs, but not all! When I typed in my misspelling last night, Safari failed to correct it. Too funny!