Why are black people always watched so closely at a liquor store?

Because the people that watch are st. Stereotypes are the worst.

Racial profiling. 
A lot of people assume that because of the forced situations blacks have been in the past, that they're all bad people. Which is not always true. Although black people can still steal(like any other capable human being), so can white people. And hispanics, and middle easterns. But based on the history of America, specifically, black people have been the most common to shoplift or vandalize. But that was in the past, anyone today can easily steal a bottle of beer or a pack of gum from any store just like everyone else. I think the issue is that most priveledged people haven't let go of the past. Or at least what the media filtered as the past.

Hope this helps. :)