People who want to 'just go down the list' of 12 wines. (and don't spit.) 'Start me at the top. I don't give a rip because I ain't buying anyway.' Drinking and driving is illegal. So is being drunk in public. The winery can, should, and will cut you off.
People who 'refresh' their palates between wineries with mint gum. Mint only destroys the sensitivity of the palate for about two hours. Eat a jalapeño while you are at it. Have a cinnamon latte to wash it down.
People who sneak out the door when you aren't looking and leave without even saying thank you. Canadians are notorious for this, eh. If there is no charge for tasting, common courtesy suggests you buy a bottle of wine at each winery to keep tasting free. If you really don't find something you like, at least say "thank you" before leaving. Don't tell us you will look for our wines in Bumbfuck, New York. You won't look and we won't ever be there.
People who say they are 'just tasting' and will be back tomorrow to buy. Sometimes this is true, but most times it isn't. To not sound like a jerk, just don't say it. Say "thank you" instead. When you show up later to buy, the tasting room employee will be pleased to see you and he/she will not have had a single bad thought about you.
People who think they can get all wines cheaper in Seattle. Large wineries have this problem where grocery stores will use their wines as a "loss leader" in order to get you to buy over-priced items while you are in the store. The store doesn't let you taste every wine on the shelf. Tasting rooms are expensive to operate. You probably won't even find the wine in Seattle. Buy it on the spot or say "thank you." before you leave. If you really like it, you can buy more later in Seattle. Actually, some of our wines are cheaper in Seattle. We will tell you which ones are. Our best wines are not available in Seattle.
People who pretend to be 'wine writers/bloggers' or otherwise take copious notes. We will treat you like any other customer - well, maybe not quite as well because you are announcing you are not buying. There are about four wine writers that count. They don't go wine tasting secretly to discover new wines for you. (Sorry to burst your bubble. The Easter bunny doesn't exist either.) Steve Heimoff isn't going to show up at Bonair with a notepad. These guys arrive on paid junkets and most wineries only get to 'kiss the ring' (isn't the Latin word for ring, 'anus?') and present their wine at a central location. Nowadays we don't even do that. We just submit them to the Wine Commission which uses them to party.
People who brag about what expensive wines they drink/own. Wine is food. Get over it.
Three men is business suits that burst into the tasting room who only want to taste the most expensive wines, but are afraid to buy anything because they don't know anything about wine and don't want to look foolish in front of their colleagues. This usually happens at the end of the day after a conference or meeting. I always admire the guy who buys a bottle of Sunset because he likes it. He has balls.
Uncontrolled children who proceed to dismantle the tasting room while their clueless parents taste wine. We have threatened to give away free goldfish to the children for being so 'good.' Hopefully, the parents will see the irony. Who will be the ogre when they have to flush the damn thing down the toilet?
People who drink beer (if you can call Buttweipper beer) between wineries. Admit it, you are an alcoholic. Get help.