Q: Fair use or copyright infringement? Can something that is an infringement in copyright or IP law also be fair use?

A: Determining fair use versus copyright infringement can be complex, but some general principles apply:

1. Using a company's logo in fan art without permission is generally trademark infringement, not fair use. Trademarks identify the source of goods/services, so using them suggests endorsement.

2. Fan art depicting copyrighted characters is a gray area. Courts have found non-commercial fan art to be fair use in some cases if it's transformative and doesn't harm the market for the original. Sharing with a few people tips the scales towards fair use, but widespread sharing may not be.

3. Simply downloading/saving a copyrighted image generally does not qualify as fair use, except in specific cases like using a small part of it for news reporting/commentary, research, teaching, etc. Just because it's findable on the internet doesn't mean you can freely use the whole image without permission.

4. Downloading/using game ROMs you don't own is nearly always copyright infringement. While some argue it preserves games, courts have generally not found this to be fair use since it allows playing the full game without paying for it.

In summary - fair use involves using only small portions of a work in a transformative way that doesn't overly harm the copyright owner. But many common practices like using trademarks in fan art or saving full copies of images/games don't meet these criteria, so they infringe on copyrights/trademarks even if intentions weren't malicious. The law aims to balance public access and content creators' rights.