Alright, most people here would say don't use liquid smoke.
There are lots of beer styles that benefit from a little smoke addition. I've used a little in a strong scotch ale and an irish ale.
I've also made several smoke beers which are very smokey. One of them is listed in my recipe pulldwown (under my avatar).
To make a beer smokey, all grain brewers add one of the smoked grains available. Weyermann has a smoked beechwood malt, and Breiss has a smoked cherry malt.
I don't know what an extract brewer would use. Maybe liquid smoke