As Journeyman Geek says, the custom flag (flag for moderator attention) is the way to go here but for more reasons than just because the image or username may be lesser-known.
We only really let users flag posts or comments. If you're flagging a post or comment because of a username or profile image... well, the moderator may not see that, even if it's something obvious. We just get blind to flags being about the content of the post, not who wrote it, so it's even more important to be clear about what you're flagging when it's not the content.
While you could support your generic flag with a comment, I would strongly discourage this. Please avoid commenting on this on the main site post for a variety of reasons:
- Comments should be about the post and should avoid meta-issues like information about the user who posted it.
- Someone may see an image and decide they like it without realizing it has a negative implication; accusing them of belonging to whatever group uses that image doesn't assume good intentions and it's just not nice.
- It draws attention and may lead to more drama, say a dozen comments arguing about it. If this content is bad, we want it gone before it becomes too big of an issue. Many people may be unaware of what it means or not notice it themselves, so drawing attention to it may cause more harm than only flagging.
If you choose not to help them, that's your choice. Please don't try to influence others to do the same through comments "outing" the user.
For those discussing whether to clear it - the answer is, unequivocally "Yes".
This is our network-wide policy. Andrew T linked to this in the comments but this should give you a good idea of how we respond to these:
As a moderator, how do I handle a potentially inappropriate profile picture?
From Tim Post's answer there, you get a pretty good idea of what sorts of things we feel are inappropriate.
Avatars are much more visible as we show them under every single post that you write, and as such, are open to a tad more scrutiny. If the avatar:
- Depicts or promotes hate in any form
- Insults, is insulting to or negatively objectifies those belonging to a certain race, gender or religion
- Otherwise creates disruptions that moderators must deal with
... then we're probably going to require you to use another avatar. The key here is in the third bullet, creating disruptions. We aren't nannies, and we don't want to tell you how to depict yourself online. However, if the manner that you choose to do it creates disruptions within our communities, we're going to need to have a chat. I can't possibly categorize every kind of avatar that we might act upon, if folks find it objectionable and we can clearly see why, then you need to change it.
The truth is, whether that image was used intentionally or not is irrelevant, only whether the image you use is found to be hateful, insulting or causes disruption. But, since we always assume good intentions, we're not going to punish someone for using it if they seem to be attempting to participate in the site honestly. We will, as I did in this case, simply remove the image so that it doesn't cause any harm and send them a note explaining why the image was removed.