When I see minimal body hair, I think "swimmer," not "orchiectomy."
Those "House"-style assessment techniques probably have fairly low sensitivity and specificity. I'd wager that you'd get way more false positives from assuming minimal body hair --> cardiac hx, say.
I think you have to take it in with the sum total of knowledge and findings.
It is a failure of EMS education and knowledge to apply 1:1 models of assessment.
If there is no/minimal body hair, there has to be a reason. That reason needs to be investigated, though not in the emergency setting usually.
Because of the slowness of human evolution, people are predsposed to cardiovascular disease. (except some east asian populations, for reasons only speculated, but likely a combination)
Along with C/V disease comes a host of other related illness. Obesity, HTN diabetis, etc.
When you examine a patient, finding physical evidence of things like metabolic syndrome will usually not land you too far from the mark.
But it is the sum total of findings and understanding of inter-relations that permit accurate assessment like this.
Another example is something like caput medusae, does it tell you if a blockage is pre, post, or intrahepatic? No. but when I see it I know there is some sort of portal system HTN. I know the sequele of that.
Now start adding other history and physical findings and your accuracy can increase considerably.
However it is all based on knowledge of phys and pathophys. Without it, your physical exam is going to be next to useless. (it has been my experience this knoledge and exam accuracy usually correlate) If you leave parts of your physical exam out, like liver/heart margins, percussion, etc. of course your findings are not going to be accurate.
I have met physicians whose physical exam are as good as any battery of tests. I work hard to become as skilled as they are. But I can say for certain, it requires knowledge and practice. Merk Manuals and simple correlation is just not going to do it.