That would surely explain some of it.
He looked, acted, sounded terrible!
Most people smoke pot like an unfiltered cigarette. Imagine smoking unfiltered cigarettes for 15 years the damage that would do to lungs. Add to that being stoned all day long for 15 years and there simply has to be massive damage. There are quite a few studies popping up now how pot does quite a bit of brain damage over a long period of time. Who knows what kind of other drugs he did. Plus it is my understanding that all the illegal pot was laced with other chemicals to make it more potent and you simply do not know how screwed up Beck is.