I have no idea what they called them before or why it might have been "dirty". I always think spring when I see them, they die out when it warms up, they are not any problem for me.
I was going to ask this very question today. We haven't seen any yet although the migration chart shows they are here. The first one was spotted around St. Patty's day. Our feeder has been out for about 3 weeks.
Hummingbird migration map
So who do all you pool owners use if you have a problem?? I have yet to find a company that just fixes the problem, not adds $$$$$ to a simple fix for other things that "might" be wrong. I'm so tired of dealing with less than honest pool people.