Is stuff like this considered 'safe'?
Full frontal nudity but no genitals.

http://e621.net/post/show/275675

That would be Questionable because of the pose, I'd expect. Ass-shots of MLP characters (nude, no genitals) are Safe generally, but if they're spreadeagled with a come-hither glance, it's Questionable.

I'd say it is.

Look at it this way, if someone clicked on that link at work, would they suddenly have to click away so that no one saw them looking?
That particular image is kinda hard to call. TECHNICALLY there's nothing wrong there, but it looks pretty clear to me that there was a huge cock there that zen just airbrushed out afterwards :V

I guess I'd still call it safe. It's just kinda weird how he has a sculpted and well defined abdomen and then a bury ken bulge down below.

elad said:
if someone clicked on that link at work, would they suddenly have to click away so that no one saw them looking?

I can't honestly imagine that anybody in their right mind would answer "no" to that question, unless the person works in a porn studio. The image might be 100% clean by every possible legal definition, but almost any boss would still have a word with the employee who is looking at stuff like that at work.

E6Help said:
All posts on e621 are one of three ratings: Safe, Questionable, and Explicit. Questionable is the default if you don't specify one. Please note that this system is not foolproof: from time to time explicit images will be tagged safe, and vice versa. Therefore you should not depend on ratings unless you can tolerate the occasional exception.

Explicit[/b]
Any image where any genitalia are exposed and easily visible. This includes depictions of sex, masturbation, or any sort of penetration.Safe[/b] posts are images that you would not feel guilty looking at openly in public. Pictures of nudes, exposed nipples or pubic hair, cameltoe, or any sort of sexually suggestive pose are NOT safe and belong in questionable. Swimsuits and lingerie are borderline cases; some are safe, some are questionable.Questionable[/b]
Basically anything that isn't safe or explicit. This is the great middle area, and since it includes unrated posts, you shouldn't really expect anything one way or the other when browsing questionable posts.

elad said:
Look at it this way, if someone clicked on that link at work, would they suddenly have to click away so that no one saw them looking?

That litmus test is why I would rate it Questionable.

That image is definitely Questionable, not safe. It's obviously ex-porn with a porno pose. The penis is not even airbrushed out all that well.