Some snakes will refuse rats that are too big, some won't. My spider girl has never had a problem with large, or even xl rats, but my other adult girls won't touch anything over a medium. It's fine with me, since I don't usually go any bigger. The only time I offer larger than a medium is when I have dead/retired breeders to dispose of.

The smell could be an issue, but I would be more concerned about the size. I'd say that 90% of the time if a snake won't eat, offering a smaller meal will get them back on track. I recently bought a breeder Mojave female and her previous owner was feeding live mediums. So that was the first thing I tried, but she wouldn't take it. So I put her in a smaller tub with a hide, left her alone for a week, and offered a small live rat. She took that. Might try a medium next time. Her belly is a bit concave, so I want her to put on more weight.