I didn't want to hijack the original conversation about models working for sites such as KINK.com, but a model brought up the difference between RACK and SSC in that realm in this post and I wanted to respond/explain since she said she wasn't as familiar with RACK.

"SSC" stands for "Safe, sane, and consensual" and it's long been the flagship phrase for much of the BDSM (bondage/domination, Domination/submission, Sadism/Masochism) community.  It's both a philosophy and a public showing of how the behavior members of the community engage in is different from non-consensual abuse.  The idea is that everyone's treatment of one another should meet all three of those criteria.

"RACK" stands for "Risk Aware Consensual Kink," it's a newer idea brought out by many who note that much of the activity engaged in by the kink community can be safer if the people involved are aware of the risks and treat them accordingly but they are still not necessarily SAFE, and that "sane" is a very subjective definition based on different standards so it's not an applicable term.  A good analogy would be skydiving.  Skydiving's not particularly safe or sane (as compared to something like 2 lovers using whips on one another) but the people who skydive (I'm one of them, as well as someone who uses whips) are aware of the risk and take safety steps accordingly to make their choice as safe as possible.  "Consensual" remains, because without consent it DOES become abuse.

Now I'm going to editorialize a bit & note that RACK is put forth FAR more by the younger crowd (under 30 & especially under 25) and those who've been in kink for a comparatively shorter time (speaking here as a 41 year old who's been in kink since most of the folks I just mentioned by age were in high school or elementary school).  While the base argument behind RACK vs SSC is sound (speaking, like I said, as a guy with whips as well as electrical probes and other somewhat out there pastimes), I have noticed that some of the crowd loudly crying for RACK is actually using it as a cover for VERY dangerous behaviors, and things that cross the line in to non-consent.  If their behavior is challenged they will tend to lash out & respond with attacks on people about being old, or fuddy-duddies, or that SSC is "for pussies," and that "RACK is where it's at."

As an example, my ex found a photo on Fetlife (a sort of Facebook for kinky people) of a woman in high heels on a tile kitchen floor squatting over an empty wine bottle, the neck of which was inserted in to her vagina.  She had nothing immediately behind her & no spotter.  That's extremely dangerous for multiple reasons.  The open bottle can for suction and become jammed, requiring the glass to be broken to remove it.  It can tear the vaginal lining, or cause a prolapse (you don't want to know) from the suction when removed.  In the case of this stunt, if the girl had slipped or lost her balance & fallen on the bottle she'd have had broken glass internally.  My ex said something about it and the boyfriend involved responded & threw a fit about "how dare you tell us what to do, we know what we're doing, you're a stodgy old person who doesn't know shit, that SSC crap is DEAD, we do RACK and this is RACK, RACK is where it's at."  This was coming from a couple of people who're 18-24 years old with less than 4 years BDSM experience collectively between them who were engaging in activity that might've been consensual but was clearly not thoroughly "risk aware."  To MY mind, "risk aware" means you take steps to AVOID the most dangerous things, or mitigate that danger... NOT that you say "We know it's risky so it's OK."

My little rant.