agrees with you: “A gorch is a large and unsightly skin inflammation to which Klingon teenagers are prone, similar to the Human skin condition acne.” Note that it lists it in the singular, suggesting that a gorch is a
pimple, rather than the condition known as acne. (M.A. cites the film “Insurrection,” which I haven’t seen, so if you are looking for a definitive answer you will have to watch the film. )
However, as with all wikis, it is prone to distortion and outright error. A pimple or three do not equal acne, and can be symptomatic of a number of ailments. Humans of all ages can get acne due to such simple things as normal hormone fluctuations and changes in diet. I think it is just more of an issue to teenagers than to any other demographic due to issues of self-image and peer pressure.
Then again, Worf is the very model of the eternal teenager, so that leads inadvertent credibility to the Memory Alpha entry.