I don't get dressed until later in the day if I need to go out.
So if I get annoying rings on the doorbell
I first look through the spy hole lens,
and if it's not the postman, utility meter readers,
or a policeman;
then decide on one of three options

a]   ignore the caller.

b]   if the ringing and knocking persists,
       I open the door slightly on the security chain
      and moan gruffly
      "This'd better be important.
       You've just got me off the toilet and I've got paper stuffed up
       my arse, what do you want !!???"

c]   if around Easter it's the elderly ladies from the local god- botherers
      I open the door and stand there with a welcoming smile on my face
      and a friendly "Good morning"
      whilst wearing nothing but a skimpy towel around my blubbery old waist...


... whatever, a firm [verging on hostile] "nah, I'm not interested"
always clears any unwelcome visitor off my doorstep.