This is all very situation dependent. I have heard of people renting out detached garages and storage sheds before but it has to have the right set up. If this is say, in the backyard of the home I would definitely not do it. As a renter I wouldn't want someone else to have access to my back yard and to not know who was on the property. If this is a bigger property, or in the city where there is very little privacy anyway then its a possibility.
You really just need to look at a few things. 1) would you be comfortable with a stranger coming and going as they pleased with where this shed is located on your property if it was you living there? Is there enough demand for someone to rent this shed or is it going to be people constantly in and out? How much is this worth a month to you Vs. how much will this make your renters uncomfortable or want to look for another place?
If this shed is out of the way and away from the main house then go for it, just make sure you make the tenants of the home aware of it before they sign the lease.