I wrote to the conference organizers explaining in very simple terms that it could be easily shown the results were wrong (i.e. "please send this to the original referees" - easy, you would think ...) One of them was sympathetic but said it can't be withdrawn from IEEE, and the other was like "get lost, I don't care". It was quite an eye opener. You really don't know what this is like until you've tried it.
I eventually wrote to the author and his work (Porton Down) saying the same thing and the author reacted quite well. Still, the IEEE site for the papers doesn't say anything. Just my comments on pubpeer. And that doesn't come up in a google search. So there are still people wasting their time reading a result known to be wrong.
https://pubpeer.com/publications/9842D9E91821B0F7CADE333BE9D... https://pubpeer.com/publications/BF67542504DA9118ECBE8869EAF...
The only (obvious) red flag for a potential reader is of course - it was supposedly a very big result, so why was it at an IEEE conference instead of a top combinatorics journal?