I usually don't (unless I expect someone of course). Between having to keep the dog away because he goes nuts, and the fact that 99% of the time, it's people who want to sell me stuff, I just ignore it... And yeah I'm sure that they know there is someone home most of the time, and it's probably rude, but sheesh... nothing like having to turn away yet another person while trying to keep the dog from rushing out of the door (he's not aggressive at all but he will try to get to the person). Just can't be bothered.
Is it just me?
Is it just me?