I first encountered this, in the form of a $1 phone charge (it was quite a few years ago!) at a Ramada Inn on St. Mary's in Tucson, which may not even be there any more. (This hotel is also the source of one of the most unintentionally funny billboards I've ever seen, but that's another story.) The desk clerk wouldn't remove it, I didn't have much time, it was "just a buck," so I paid - but never went back, despite frequent trips to the Tucson area.

My take is that a rate ought to be what you pay, plus taxes, unless you voluntarily choose to buy more. If there's a sign by the phone that says "pick it up and you're out $4, but then you get unlimited local calling" it's fair. To check out and see a $4 charge, or even a 4¢ charge, for a phone you didn't touch is not fair. It's like the inkeeper in Les Miserables (the musical, not the book) who sings about the extra charge for looking in the mirror twice. It's fundamentally dishonest.

Clearly posted optional charges that are added to your bill, but which you're told up front will be removed on request, are a different story. Some hotels (a recent Sheraton comes to mind) add a $1 charitable contribution. Also, on a December trip to Israel, I saw optional charges of about $1 at hotels and about 25¢ in restaurants to defray the cost of hiring security guards. A back-of-the-envelope calculation says they're more or less breaking even if everyone pays. As far as I could see, everyone did. (The Tel Aviv Hilton didn't ask me for it on an award stay, but I wouldn't have minded if they had, and I would have paid.)