There ARE a double handful of behaviorally-linked cancers among the bathhouse/glory hole crowd like anal and throat cancers (from HPV), hepatocellular carcinoma from HCV (Hepatitis-C) and it’s curious that the article references cancer four times but doesn’t mention what KIND.
And “gaydar” has about a 70% concordance when actually tested.
Those are odds you could take to Vegas to break the bank.
For me, they telltale sign is in their eyes. Even when they are looking straight at you, their attention by their eyes seem to be beyond you.