I think there are a few issues here:
young drunk men
antidepressants like prozac/zoloft/most SSRIS
post manopause men.
If you're using antidepressants: SSRIs tend to have a side effect called "retarded ejacualation" in many men - meaning you go from 5 to 50 minutes to come on your own, and 15 to never with a partner. Wellbutrin tends not to have this effect, due to its different chemical attack plan.
If you're a young heavy drinking man, you either have a fine acting penis, or you know that it works after 10 beers but not 16.
If you're an older man, you will know how many beers, antidepressants, fights with wife/husband, and recency of performance affect you.
If you are young enough to be experiencing "whisky dick" in any form, start learning. If it is booze, antidepressants, mood, or age, it is something your body does, and is not going away as you get older.