This may be a cultural thing, but:
- Interrupting things to ask 'how things are'. Come over and ask, if you must, but not while I've got a mouthful of food or are mid-conversation.
- Constant refills. If the glass is empty, OK, but not after every mouthful.
- Unrequested new bottles (of whatever drinks).
- Asking for some sparkling water for yourself, and finding it distributed to everybody around the table, when it's only you who's going to drink it.
- Ridiculously long specials lists recited at your table. I can't remember them, it's nice you learned them, but really, it'd be better written down. Oh, and put some prices down, please, particularly if you're planning on charging a premium for them.
- When you get poor/snooty service for not ordering wine. Yes, I know you think I'm cheap, but actually, neither of us drink alcohol, for very good reasons.
- Service charge plus tip request. One or the other, please.
- Accepting special offer vouchers etc with bad grace. This seems to be a recent thing, but is extremely annoying. If you don't like it, don't offer it.
- Tables too close together. An intimate atmosphere is nice, and I'm sure space is at a premium in this city... But if I'm out with my wife, I want to talk to her without the person a few feet away listening in.
- Sunday Evening Syndrome. "Oh, I'm sorry sir, we're out of that." OK, you can't always predict volumes 100% accurately, but please let me know up front.
- Acoustics. I go out a lot in London, where people do like the sounds of their own voices. So, if you have a small space, perhaps underground, decorating it with plain white walls and wooden floors will have a deafening result. The addition of music doesn't help. I don't want to have to shout to speak to the person next to me (and not be able to hear anybody else on the table).