I've downvoted every Incubus song that has ever come on my Pandora radio and it insists on trying to keep playing more Incubus. It seems the more I downvote one song, it tries to play different Incubus songs. What is going on here and how can I train it to understand my hate for Incubus better?
Look at what station you are listening to. If it is a band or song really similar to Incubus, delete it and replace it with something else.
Also, you can look at your whole thumbs-up/thumbs-down history if you go to the station menu and click "Edit Station Details." That might give you an idea of why Pandora thinks you like Incubus.
Amendment: If you REALLY don't like them, get rid of any and all thumbs-up you may have done in the past for their songs.
When it plays an Incubus song, click on the "Menu" button and select "Why was this song selected." That's probably as good as you are going to get. The songs by Incubus probably have qualities which are similar enough to the songs that you have Thumbed up.
I've noticed that Pandora sometimes takes the wrong path.
I've voted on well over 300 songs for one of my stations (No, really! See here), and I still find that Pandora plays the wrong kids of music. When this happens, I simply Refresh my browser and start over.
For some of my smaller stations, I will start over. Clear all songs which have been thumbed up or down, and try again. I usually have better luck the second time through because I'm more careful with which songs I select.
I've read of people pranking others in the office (or at home, perhaps?) by going by their computer and giving a thumbs-up to artists they know the person hates. Check your station details and make sure there isn't an Incubus thumbs-up hiding in there somewhere. Based on my experience with Pandora, it appears that one thumbs-up for an artist on any station makes that artist more likely to appear on any other station, if the style fits reasonably well.
Giving an artist thumbs-down twice on a given station bans that artist from that station. But it's something you have to do separately on every station, and it only works if that artist isn't already listed in that station's seed songs or thumbed-up songs. If you have a seed song or thumbs-up song by that artist, the two-thumbs-down ban won't work until you remove those seed/thumbs-up songs.
One final tip, if you're on a PC running Windows: Windows + L. This key combination locks your computer. If there is someone pranking you, Windows + L will prevent that person from messing with your computer while you're away.