In a situation that recently occured, I purchased a Truegold transmute from another player for 100g, my mats. He procced a second Truegold Bar, but only gave me 1 of the bars. I was upset. I would never pay 100g for a transmute specifically from a transmute-specced Alchemist only for them to take the proc. The man then continued to return to me the 100g tip and hoped I went on my way.
I didn't.
He in essence stole 300 gold from me (It may be petty, but there's a matter of principal involved). I have an open ticket as he still refuses to give me the bar in exchange for the 100g tip I gave him with the materials I traded him.
This leads me to a question, however: Should a buyer of a tradeskill have to specify that they receive all the items that are crafted with their materials?
To me, it's the same as if I were to give an Alchemist the materials for 20 flasks and they only gave me 18 in return. I gave them the materials, they used them in their craft to make a tangible material, then only gave me a portion of what was crafted with my materials. To me, that seems like stealing.
I'd like some other opinions on the matter, though.
-=EDIT=-
Not going to answer the same questions over and over. I'll post several facts below:
1.) I asked specifically for a transmute-specced Alchemist
2.) He approached me, not the other way around.
3.) He returned the 100g to me that I paid in tip after he procced one.
4.) The man in question actually returned the second Truegold Bar in a mail, apologizing and admitting he was wrong.
5.) I did pay him back the 100g I gave him as the initial tip.