Things you could dump over McCain’s grave without getting caught...
https://www.cabelas.com/product/Tinks-Skunk-Scent/745931.uts
https://www.amazon.com/catfish-stink-bait/s?page=1&rh=i%3Aaps%2Ck%3Acatfish%20stink%20bait
Feel free to add your own.
Any of those above will assure that nobody stays at the A-hole’s grave long.
Unfortunately that would impinge on the sites of the poor souls interred around him. Wherever that may be. He could be buried in the prison cemetery at Leavenworth, and those around him, criminals all, would still have been better men.