They actually make good leaf litter in that the leaves curl into a tube shape when they dry out. This makes for good hide spots and keeps the leaf litter from being too much of a flat wet mess. Their durability is somewhere between magnolia/live oak and maple/large leaf oaks (red, white, chestnut, pin oaks, etc.)
Personally, I wouldn't use them if they spray anything anywhere on the property.
Most likely they would be spraying insecticide, as in kills bugs ie springtails, isopods, fruit flys, etc. Even if they didn't directly spray the rhodos, I was a licensed pesticide applicator for a few years, over-spray and wind drift happen.
Amphibians are also very susceptible to many pollutants/poisons even at levels that would be safe for other types of vertebrate animals. I'd even be worried about herbicides like glyphosate (roundup) which is relatively inert to people and mammal type pets.
Bottom line, if there has been any spraying, is it really worth your pets lives to save a few bucks on leaves?
Sorry if that came off as condescending or preachy, wasn't trying to be.
As others have said, Rhodos/Azaleas are decent medium durability leaves so if you can find some that you know are clean, they are a nice addition to add variety to your leaf litter. Might be worth adding a few to your yard for the leaves. They have big showy flowers too during the summer