betadine or any chemical anti-septic is and can be harmful, if ingested in large amounts. which the chance of a snake doing that is rare. usually if they are dealing with scale rot, they dont wanna do much such as move around, eat or drink, etc. so if they ingest a little its not a huge deal, and most of them will not just sit there, soaking in a tub and drink. they will keep their head up resting on another part of their body, and like the relief of soaking on the ventral scales that are infected