I use one often to meet people at for the first time...It is a little different and the 6 channels of XXX-rated videos add to the charm

I call it my oldfashion pay by the hour no tell motel

I would say you would be better of checking 20 miles outside of Boston..They are not fancy  places so check around other adult locations like a strip club or a porn shop. Ask the clerk if he knows of one

Good luck and have fun
Kisses Haley

and found that there are no "hourly" hotels listed.  I suspect that you'd have to drive to a "questionable area" and look for hotels that cater to transients.  

I did find some hotels that, while not hourly, may have the atmosphere you may be looking for.  Although, for the life of me, I cannot figure out why?  

http://www.travel-library.com/hotels/north_america/usa/massachusetts/boston/farrington_inn.html

This one is considered a two star hotel, with an average user rating of "1" and here are a few of the comments:

No matter how small of a budget you are on, this place is not worth it. I just spent a day at the clinic being seen for bed bugs and pinkeye that I got from the filthy farrington. The sheets were nt only not fresh- they had fresh stains of bodily fluid on them and were sprayed down with cheap cologne. What I saved in money I lost in health, time, medical bills, and prescriptions. Bad place, bad management, bad location. Honestly, it should be shut down by the department of santitation.

I have travelled many times to the third world and have never seen any hotel so filthy. The entire hotel smelled like mold. The bedding was filthy, dirty and stained. I had to sleep with my pillow wrapped in an old T-shirt and my pants on so my flesh would not touch the sin covered sheets. Cigarette butts litered the front steps. No towels were available. I pre-paid for two nights and left after the first. This is truly the most rotten hotel in the universe.

Here are other cheap 2 star hotels.
http://www.kayak.com/s/hotels.jsp?completed=true&searchid=7mgmXzry1YdNRU$CnGWaCg

I'd be afraid of catching head lice or bringing home roaches.