They need to have a sign that says "gratuities appreciated". That eliminates the need to tell people.
I've never used a skycap, but on a related note, several years ago I went to a California Pizza Kitchen in southern California with 3 other people. The service was very slow. Then to add insult to injury, it took
45 minutes to get our check after we were done eating! That was the worst service I have ever had. I left no tip, something I have never done before. Underperforming service gets a low tip but just ignoring me (I would probably still be there if I had not kept bugging the server for the check) gets ZERO.
When we walked out the door, the server ran out and complained that I didn't tip him! Unbelievable! I put California Pizza Kitchen on my ban list for that.
