I'm really unsure of what is causing this. I do not use too much fertilizer for sure, and I own about 22 'epi' plants and the only one thats looks this way is a 'King Midas'. If a more experienced 'Epi' enthusiast could jump in to help me out, I'd be very thankful... :)
I find brown spots on about four of my epies. My King Midas is OK. German Empress, King of Yellows, are two that I remember with spots.
If there is scarring it's probably snail damage.
Several Epie species have this spotting as part of their normal growth. Sometimes you can cut out sections and make your whole plant look better. I have one, however, that is actually covered in brown spots yet appears to be very healthy and strong. Go figure. bob