Patrick
My take is as you put it the price reflects or still under the actual grade I think that says a lot. I'm just a collector and for 40 years so I should be able to put a grade on cards as best as anyone but in all the years of trading I have never put a grade on anything even trading with you. I always send pictures and describe the flaws and let the other person decide the grade for themselves. Everyone still grades cards a little differently I look more at the price to see if it reflects the grade I see. What you are describing is some deception but ultimately if the price is accurate I don't see even leaving negative feedback as some suggested.
I say move on and do whatever you want with the cards. Rick
PS. On the other hand by what your saying some people could say you were only going to be happy because you thought you got a great deal. I wish I could make a profit on every deal I've made.