There was a thread once upon a time that discussed the propriety of being a server in a restaurant and having to deliver alcohol according to the requests of the patrons. I suppose working as a clerk in a convenience store or grocers might, to some, be a gray area when, for example, someone brings a case of beer or a rump roast to the register, but I very much doubt that it runs afoul of the precepts. However, one career field which I think does run afoul is sales and advertising. The purpose of those endeavors is to generate desire in another person(s), and I find this to be very much more against the Dhamma than operating a cash register or walking a beer and a burger from the restaurant kitchen to a table.
In this analysis my understanding of Right LIvelihood begins to take shape:
Brewing alcohol? Problem.
Acting as an advertiser for alcohol? Problem.
Bartending? Potential (context-specific) problem.
Delivery driver of alcohol? Potential (context-specific) problem.
Ringing up an alcohol sale as a grocery clerk? No problem.
Examples are probably to be examined individually, in these complex economic times. Also, you could always go forth...