mpyw
Did the buyer ask you about the condition of the CD Player?
If he did, or if you made any statement to the effect that the player functions properly when you knew that the player intermittently failed to operate property (failed to read CDs) and if you failed to disclose or concealed that aspect of its performance when you knew that such knowledge would necessarily have an effect on the purchase decision of a reasonable person, and you concealed or failed to disclose such information in the hope the buyer would purchase your defective CD Player, then I think it might fairly be said you defrauded the buyer.
The fact that you proposed that the buyer test the warranty instead of doing so yourself does not, in my opinion, alter the fact that you defrauded the buyer nor does it justify your conduct.
As to your report that the buyer thanked you and told you how nice it was to do business with you, well, piss on some folks and they think it's raining.
So, for these reasons, to answer your question, if you had done this to me, would I be pissed off?
You betcha.
