An easy way to check if dry bud has mold is to break it up like your going to roll a joint. Moldy or rotted bud looses its consistency. When you break it up you will feel that the rotten but just falls apart. Another good way is to buy a magnifying glass or small hand held microscope. they are only like 20 bucks. Then you can clearly see the affected area. Through a microscope rotten bud will be evident by the degraded trichomes. They trichs will be way way more amber than the surrounding unaffected trichs. I deal with bud rot all of the time due to the fact that I always grow outdoors in the summer and I live in Florida where it has rained almost everyday since June 1. The best way to fight it is to use a small amount of liquid copper fungicide, but I only use it until the buds are about half way and then I stop because I don't want to smoke that shit. I have had pretty good results. This year I grew some funk. Still have some drying that I just chopped and it had some bad spots on it. I just looked it over good and cut out any rotten bud. I also found a bud worm crawling on my drying plant this morning. I think he was high as hell because when I pulled him off he didn't move. They usually curl up when I pull them off but I think he was passed out.