it also helps if anybody finds a questionable image (usually involves bathing suits or conveniently censored nudity) please mark it as questionable.

Omnomnom filth.

What is the line for questionable pictures?
I think that most pictures with tags like, for example, panties could be deleted but I dont want to flood the flag inbox to cause unecessary work for the mods.

I don't think there is a perfectly clear line between what is questionable and was is unsafe. My point would be a picture can be told unsafe if the drawer could have turned it into porn with just a minor add.
For example, if you see a drawing of a girl lying on her back, her legs widely spread with a bitchy face, even if she has her panties on, it's obviously unsafe. But we can't decide all pictures showing girls with only underwears would be unsafe. Some of them are just cute or sexy ; and don't mean to be deleted.

As a conclusion, I would say no rule can tell you what is safe and what is not (except obvious porn like penetrations or so). The only things I delete as a mod are sexually suggestive pictures and disgusting ones (like inhuman showing boobs or ultramassive fat butts). I try to respect all pictures that are SFW, even those who doesn't fit my likes, and delete the less pictures I can. =)

Thanks for replying so fast.
I didn't mean to stereotype all pictures with the panties tag as deletable(the tag itself being merely an example), but most pictures I see with that tag are obviously with a clear sexual intent (that means that there are indeed pictures with the tag that are simply artistic, but I have the tag filtered out anyway to avoid said majority). Personally, I'd delete every picture that you obviously wouldn't want to be seen looking at by your family/co-workers (which is basically the whole definition of safe for work), but seeing that some of the admin's favourites even fall under that, my preferences are a bit too strict. Thanks for clearing that up.

Okay, I think that this has gone quite enough. This Sanae pic safebooru.org/index.php?page=post&s=view&id=848214 must be nixed and stat! Not that I am demanding or what have you but I really do care for SB's sanctity.

Just for clarification, may I flag string bikinis, scantily clad, and suggestive of gross disrobing?
Do we just need to accept that some whole characters, in their normal outfit as Felicia from Darkstalkers and Liru, are simply unsafe for work?

I actually don't think that Felicia's costume is NSFW. It's allowed into a lot of conventions as cosplay when done accurately, however, there are a lot of artists who would like to change that up and make it a little more revealing than we would like. That's where the problem lies.
Just don't go around like this one person we had and flag everyone in a bathing suit, covering or not. That was a pain to go through. We pretty much have to use our best judgement.
I'm a little more lenient, myself.

G-strings, string bikinis, and sling bikinis /might/ be NSFW but not always.
I've always thought Felicia's costume as somehow tamer and less sexual than Morrigan's or the Disgaea girl costumes.

I suggest using the flag for deletion option in future, much quicker and efficient for all :)

One of these posts exhibits a thin, barely covering bikini top and the other clearly visible nipples. Neither are what I would call safe for work because if I'd had either on my screen at work, on a personal electronic media device, I would probably get a warning or probation.
safebooru.org/index.php?page=post&s=view&id=883310
safebooru.org/index.php?page=post&s=view&id=885120

But after two weeks and several attempts to flag them as quiestionable and NSFW, they're still up. How are these safe, based on what we've just discussed?

Okay, this one confuses me.

Is it any cameltoe image, or is one that's clearly sexual and not just "eh, you see it". Because I can flag all the listed ones easily if you want me to.

Cameltoe is by default mostly sexual suggestive so feel free to flag it.

Alright. Thanks. If any aren't, they won't be deleted, I'm sure. XD

Oh yes and flag all the other pics for showing too much leg ;p