The answer to whether or not used strap on dildos are legal to rent is not a cut and dry answer. It mainly depends on your country, state, or local laws and regulations. In most places within the U.S., the specific question of these sex toys falls into what can only be described as a gray area. Checking with some form of local authorities before considering renting them would be wise. Renting a used strap on dildo is a near perfect example of bartering; a personal transaction if I may put it that way.
State laws and all associated regulations do not typically apply to such things. Law enforcement however, could still view it as a 'commercial transaction', so knowing the current laws (if any) preceding an agreement of any sort is important. The possession of a strap on dildo itself is legal and should remain so in the majority of places. Possession of various adult toys is legal, but the renting part - at least to my knowledge - is where the more strict laws come into play.
States have and are creating laws that prevent the sale, offering or near constant distribution of what they define as obscene materials. Alabama, Arizona and Georgia being prime examples. Alabama has very clear language in their criminal code (Section 13A-12-204) prohibiting the renting, offering for sale, or even possessing with intent to sell any device "primarily intended for use in connection with sexual activity". Arizona follows a similar line of thought under their Revised Statutes. Georgia to my knowledge at least, has all the same or near identical prohibitions. Renting a strap on, or any other type of sex toy, will always remain a legally and ethically complex issue to me.
In other states such as California, the possession and rental of sex toys is legally allowed; 'obscene' being the only exception if the state deems them so. Sex toys have become more accepted in recent years, but it is still important to remember that their use (in any form) is not considered fully proper within all social settings.
Laws concerning the renting of used strap on dildos are perhaps the most complicated - physical stores, online stores, and even private transactions all have or can have variously applied restrictions on this type of rental. Shortened to the point of simplicity: possession and to a large extent use, of used strap ons is legal, renting them however may not be. Knowing what the specific laws are in your area is essential, legal or not, before attempting to rent them. Avoiding all potential small or large legal issues should be a priority.
