I am 48 years old and for the last year maybe, the front wall of my scrotum seams to be much thicker than it has ever been. It will leave a yellow mark for a moment when touched. There is no pain or odor or any other thing wrong. I am guessing this is just old age.
Have you gone to see your doctor on this one? I have seen, touched and been very intimate with many, many scrotums and have not seen this sort of thing - at least not the yellow mark. I have had a few men as clients (I'm a massage therapist) who were older and tended to have thicker skin around their balls.