I've had thousands of pm's go back and forth - me sending them - and receiving them ...I can only think of 2 that were negative - and those people ended up being banned for one reason or another. I can say that in all the pm's I've sent OR had ....they were all great - it's a good way to connect with people
I try to send out personal messages if someone is going thru a really hard time or lost a pet....and ok - I admit it - just to gossip too LOL
I can't see anyone being negative over a compliment and would have to think the pm was misunderstood...maybe it was worded so that the person didn't know they were getting a compliment ?