Dear Watson,

I would dearly appreciate it if you were to wipe your feet before walking into the apartment we share on Baker Street. While footprints, in most cases, are highly important, your carelessness concerning our carpet and mudstains from London's streets is bothering me, as I am constantly getting sidetracked with finding where you've been all day. I know of the dog that you've been considering and I highly advise against it, a dogs, much like yourself, track in mud and I do not think that I will be able to withstand such a mess in our lodgings.

Sincerely,
Sherlock Holmes

p.s. I do wish you would consider our landlady, Ms. Hudson, as well. She is almost as fed up as I with the mess you've been tracking with you.
p.p.s. Do you think red looks good on me?