I never used to use bellman, but since my wife became sick a couple of years ago, it's now standard practice for me. We often have a few beers leftover, and sometimes a partial bottle of liquor. I have never had a problem with a bellman accepting leftover beer (or even more surprising, partially consumed bottles of hard liquor) as part of their tip. From what I've learned of the bell staff at most hotels, even if you aren't going to use their services for your bags, they'd love the beer!