Being from Germany and the concept of fair-use not being something that is used there at all, I always properly attribute images I use in answers with the source and the author.
Example: How is human waste taken care of on commercial aircraft?
Since most of the images on Wikimedia Commons or other sources are published under Creative Commons licenses, I happily provide the requested attribution below the image, abusing the available HTML markup in StackExchange to provide a non-intrusive attribution line:
<br><sup>(Image Source: <<Name of Source with Link>> - Author: <<Name of Author>>)</sup>
producing below the image:
(Image Source: http://avation.stackexchange.com - Author: SentryRaven)
In a recent discussion with another member of StackExchange, we discussed if fair use can be used on virtually any document or image on the internet, since SE and IMGUR are hosted in the US. The question whether this is the case or not should probably be asked in a separate question, but as far as I understand, under fair-use an attribution of source or author it not required.
My question however is:
To form a best practice or good standard, should we try to attribute images properly and should we encourage other users to do the same in comments or attribute images/replace images where we can identify the source quickly?