Dexter's started to bark occasionally when someone arrives at the house. He even did it to my partner the other night when he got home from work. I think he was just startled though as he was asleep on my lap at the time. It's not very effective though, he goes all barky and as soon as the person sees him they go 'awww isn't he gorgeous' and then Dex just melts and goes 'OMG pat meee!!' .. lol.