The issue is that the mods aren't exactly being very clear about which fetishes you're allowed to flaunt in here.
You can have a fetish about anything. Feet, hands, boots, anything. Fetishes aren't the issue. It's overtly lewd images, or images with an implication that something sexual may be going on.
It could be a completely SFW image, but if someone posts it because it's implying something sexual, either within the image yourself, or along with text you're posting, maybe just don't post it. Rather than push and see if you can get away with a post, just don't post it.
Not necessarily accusing or calling anyone out, but if you think someone, somewhere, can take it the wrong way, don't post it. Fan art usually starts off safe, but usually doesn't end up that way. It ends up being a slippery slope leading to more and more lewd images. It's like a game of one-upmanship, sometimes.
It's a little stricter here, I guess, because smash is a 'family friendly' game, and Heath has personally said he doesn't want lewd/sexual stuff filling up the thread.
Also:
https://twitter.com/sprsk/status/509897405378994176