This profile only posts porn! Backplane already erased lots of his posts because it got too many reports, but you can see it's a porn account. (@gaycaliente69)
What really matters in these situations is 'intention' and if that 'intention' is coming across. Lady Gaga would never market herself as simply porn hence we never interpret her work as pornographic, however, the lil monsters who post nudes or half-nudes do not make their intentions artistic. By all means post photos of yourselves but put some thought into it! Play with the conventions of porn, satirize it, venerate it or parody it! But don't just re-produce it and expect to be called an artist...
I don't see anything wrong wiht those pics expect for the one in the middle. The other two is nothing wrong. Some people just love to show their body cause they're proud and that's a good point. I haven't see porn. I'm sure Backplane takes them off as soon as they see it