I think that this whole concept of forever slicing and dicing SEO into ever more precise, specific and narrow colour-coded categories is less than helpful and just serves to confuse what is essentially a fairly straightforward topic.
However, trawling back through the online archives I see that generally speaking 'pink hat' SEO is most often described as the process of partially revealing sites content in an attempt to 'trick' Google and by sop doing multiply the traffic delivered.
In other words, pink hat SEO is really no different to black hat SEO...
Look, you either do SEO the 'right' way or you follow the dark path and take your chances. It's as simple as that, forget all this colour-coded crap.
This is the first time that I am hearing this term and it would be interesting to know if there is anything out there that is called pink hat seo. I will be keeping an eye on this thread to know about this new thing in the world of search enging optimization.