Do you say Thank You?

I respond as quickly as I can and with as complete an answer as I can muster. I really don't spend any additional time wondering if the info was useful or not or if I'm going to receive a thank you.

There's been a few more responses since I piped in yesterday. First, I'm with all who are annoyed at the folks who don't include even a first name (or puncuation for that matter). Second, the only people who really spark a hair on my neck to start on fire ( for lack of courtesy) are those who refuse to even acknowledge my presence when I hold open a door. I hold doors consistently for others (looking to see if anyone is behind me is standard in exiting a building), often waiting a minute or so for elderly. A nod or quick thanks happen about 75% but some people just act "entitled" to my act and ignore me completly.