I was in the middle of the allergy season from hell and my nose was running pretty much 24/7, so I pull out a tissue.
"Do you blow your nose a lot?" He asks me. What had moments before been a completely normal conversation suddenly took a sharp left turn down Crazy St.
"Yeah, lately I kinda do." I laughed.
"How much do you blow your nose?"
"My allergies are killing me, so I guess pretty often."
"Are you sneezing all the time? Are you using a lot of tissues?"
"Kinda. Hey, did you see that news story about the-"
"-What are you allergic to?"
This continues on for like five minutes. Him asking questions about my allergies, and me pointedly trying to change the subject. The man just did not want to talk about anything else. I walked off to "browse" (IE, to get away from him) and when I came back, the first thing he asked was whether or not the dust on old books made me sneeze.
As it turns out they had lost my book anyway, and I left empty handed. On the way out snot guy asked me for my number. The next time I came in he was gone, so I guess it wasn't just me he annoyed.
It wasn't even so much bad_service as it was WTF_service. I used to work with kids who had Autism and Asperger's, and I had a good share who would get stuck perseverating on one topic, so that was my initial guess...but never were any of them obsessed with talking about mucus.
My only guess was that he was the son of an allergist, and he was trying to drum up some business? Weird and kind of inappropriate, if only because I made it so clear I didn't want to talk about it, and he kept pushing it.