Events colors have a few events displaying wrong

This has been a recurring issue. Occasionally an event is not displaying the correct color. For example, all events marked 'golf' are green. Most of the golf events are green, yet we have two events marked 'golf' (not marked anything else) and are showing up red. Likewise, I have another event in a category that is displaying wrong, though some of the events in that category DO display correctly.
Please help, my client is getting extremely frustrated (as am I).
Thank you