Apparently after a few albums Kerry King decided to take guitar lessons to help him write better solos because he was being laughed at for having shitty solos. On the very next album the next album afterwards the opening bars (or whatever) of one solo (might be 'War Ensemble', who knows) were were exactly the same thing he'd been taught in his first lesson.
I've grown to dislike Slayer's random solos less over the years. I find the experience is made better when you focus on the backing track rather than the solo. The rhythms accompanying the random solos are usually pretty sharp, the solo then becomes merely texture.