Xander doesn't purr when he's happy... he drools.
Also, when I brought Marzi and Maddie home, Maddie made a bee line for my bed and went under and REFUSED to come out. Marzi wandered a bit more..... but began to drool profusely. Seriously, I thought he'd found something and had tried to eat it and failed and had it hanging off his chin. No, no such luck..... it was drool. Foamy, white, santa-beard/merlin-beard of drool from being so nervous.