A query tells me about your book, and about you. Sometimes after I pass on the query, I discover something that makes me think "whew, bullet D O D G E D, thank you publishing deities, both foreign and domestic."
Here are six of them:
1. You reply to my auto-respond vacation notice with a screed about lazy-ass agents.
2. You self publish the novel and are later found to have sock-puppeted most of the five star reviews.
3. You answer a form reply to your query with an assessment of my taste and character that leads me to wonder why you queried such a cretin in the first place.
4. You approach me at a social function, poke me in the name tag, and hiss "you rejected me!"
5. I slink around your website and Twitter feed and notice you post who you've queried and what their responses are.
6. You added me to your mailing list without asking. Special bonus points for sending a newsletter with no "unsubscribe" button.
All of these make me glad I said no.
Notice that none of them are failure to follow the directions, spell my name right, tell me about your novel in the query, or other mistakes/oversights that are NOT the sign of an asshat writer.
Bottom line: if you're worried about being an asshat, you most likely are not.