Based on my observation from my experience. Alcohol certainly helps and loosen things up. I know my wife tends to be more flirtatious when she has taken a few shots or drank a few cocktails.
It all depends on the wife too if they connect with the guy(s) that are flirting back. I know my wife is very selective and she wouldn't open her legs to anyone, but me. Addition, the wife may be more tolerant to the amount of alcohol she consumed, to some it may come easier while others are more difficult.