I tend to believe it was an accident, given the miniscule amounts of vaseline applied, as well as the fact that we've seen GSP's 'inner energy' technique used by his cornermen in the past.
very well be, but it also completely ignores that the majority of greasing by fighters is done before
a fight. It does not change the fact that GSP feels unnaturally slippery to many fighters, including 4 former UFC champions. And they've publicly said so.
To me, to simply discount it all as hurt feelings or jealousy is lazy. They've all lost fights before. But I guess the loss to GSP for some reason required a fictional excuse? Ok. Maybe. I personally doubt it. I despise Hughes, but he doesn't strike me as a liar.
GSP is a phenom. Could his natural skill set have allowed him to beat the above fighters without greasing? Absolutely. Did he beat them without greasing? I personally have serious doubts.