Is there are place to report missing/incorrect album art to the iTunes team? I know there are various ways to get/replace album art in iTunes and other questions about that. Some of them don't provide as good quality art as from iTunes (Store). Some of them also inflate file sizes by putting the image in each album. However, one thing I've noticed is that sometimes art gets updated in the store to better reflect the CD I ripped, or missing art becomes available. For example, Bob Dylan albums used to always get the ugly "Bob Dylan Collection" cover (same for each) whereas now they get the real original covers.

Is there somewhere to report mistakes and omissions to the team responsible? It seems that overall quality could easily be improved if Apple accepted "bugs" on this. The mistakes often seems quite strange - for example, the album is in the store with the correct artwork and yet you get the wrong art downloaded or none at all. I recently got correct art for an unusual independent artist who I thought had self-published his album, followed by nothing for Phil Selway's much more famous new album. This album is available (correct art) in the store!
you can always use Apple Feedback page to submit any kind of request.

if you have this problem in our own iTunes Library, it is easy to assign a new cover to the song or album by just dragging the cover to it or using the GetInfo option, you know how to do this right?

if you install Last.fm app you can simple play a song and then drag the last.fm cover into the artwork of the iTunes song.