I ship UPS with zero issues...I print the label at home, and bring to a UPS store or Staples UPS drop off...they never ask anything if it's already labeled. When you create the label, you are asked what you are shipping, just don't say beer...I have used "glassware samples", "Hot sauce", "snow globes", etc. The only time there is an issue is if UPS breaks beers and the box leaks...you can't file a claim for the value of the package in that case as they will deny it for shipping beer.
However, saying that, a friend told me he got into a battle with UPS over a damaged box of entries he shipped from east coast to Alaska. UPS would not pay his claim because he shipped beer, he argued how to you know it was beer? They were "well it says in our report it smelled and looked like beer and we don't allow alcoholic beverages" He then responded with "how do you know it was not non-alcoholic beer or just non-alcoholic malt beverage (like canned wort you can buy these days)?" And with that, he had them, and they paid out his claim!