Well this scam is something I would never do simply because I'm not an *******, but basically I had the chance to many times and I thought why not post it here...
I'm an alchemist and I would often get asked to transmute primal mights, well basically when you do this for someone they give you a:
primal fire
primal water
primal earth
primal mana
primal air
then your supposed to make the primal might for them and they tip you...
To go through with this scam simply don't give the primal might to them to them...
you can also advertise in trade "Transmuting Primal Might pst!" but after a few times you'll very likely be hated on your server and no one will trust you so I dunno how many times you can pull this off.
Oh also you don't actually need Alchemy, people very rarely actually check the armory.
so thats about it, this scam will work 100% of the time because your simply abusing peoples trust, have fun!