Our Rabbi visits once a month. I've had thorough rabbis, cool rabbis, and mean rabbis. I've had Rabbis turn on the oven or participate in the process occasionally. Don't shake their hand! I had one rabbi who would constantly make degrading comments about women and told me I was inviting him into the bedroom by shaking his hand. He did mention that if there had been a man working he wold have shaken his hand twice, once for me. If hand shaking is an invitation into the bedroom, I'm not sure why it's more okay to do it to a man (TWICE!). In general, rabbis are people and like most auditors/people, they are generally super respectful if a little condescending.
What I find more interesting is what happens if we give someone something that isn't kosher. If we give someone mislabelled allergies, we'll cause a potentially fatal reaction, but what happens if you eat food that isn't really kosher? Do you go to hell? What if you never even learn its not kosher?