[sukilot]

Why would such a bar have any repeat customers? The music is loud at a bar because the people are loud because the bar is crowded.

If bars wanted to sell more drinks, they would have more bartenders to reduce the wait times.

[superme]

There you go: http://www.theguardian.com/science/2008/jul/19/medicalresear...

It mainly happens in busy city bars/pubs, where repeat customers aren't so important.