I keep Stan trimmed, it's not just the poo that gets caught, he sometimes sprinkles himself too
so he has a year-round sanitary trim. I started with scissors, moved up to DH's beard trimmer (he doesn't need it
), last night we used the full sized plug in clippers.
I got him used to the sound gradually by turning on the trimmers when he came into the bathroom with me. DH helps by holding (and distracting) him while I do a quick trim. I don't shave him totally, just enough so the hair isn't covering the exits.