As I have worked on ships, and sailed on over 100 cruises I think I can spot a good or bad employee immediately. I can tell when an employee cares about his job or when he is just going through the motions.
As our Linda (Trip) has pointed out, two people can go on the same ship and experience completely different things. Ship's staffs vary a great deal from line to line, but people are people so a staff on a cruise ship can vary a lot as well.
If you are used to Carnival and like that kind of very friendly crew interaction then you may be put off by Celebrity or Princess where they tend to be less intrusive and do their jobs more quietly. Its kind of hard to explain the difference, but on Carnival they try to treat everyone like old friends and they are about getting people involved. They joke with you and may ask you questions about your day, etc.
Personally, I think Carnival has some of the best crewmembers anywhere. They treat them well and they enjoy being on the ship. I know that is surprising for one of the most mainstream lines in the business, but I believe this.
On Celebrity and Princess they are more serious and refined, focusing more on giving you service but not really getting as personal with you. I prefer this kind of service (Im not much of a small talker) but I completely understand people who prefer the Carnival kind of service.
I have run into a few less than friendly staff people on Princess, but I don't go on a ship just to interact with the staff. IN my mind they are there to do a job, not to socialize with me. I realize that is a bit of a jaded view for this board of very experienced cruisers but I don't think my view is unusual for many less experienced cruisers, - ANYWAY....
I have also encountered a few less than friendly staff people on Celebrity. One Maitre' D floored me with his attitude on Century.
One thing that comes out here is that the smaller and older ships seem to get the bad apples. I am saying that while the majority of crew on a small ship may be great, you are more likely to meet a surly Maitre' D or shorex on a small ship. They weren't put on one of the smallest ships in the fleet because they are so great at their jobs. Let's just say that when I run into an attitude from a staff member on a smaller ship I am not surprised. This would be Sea Princess or Celebrity Century, for example.
I also never let one bad apple ruin a cruise for me. I talk to the staff people who seem to want to get to know me, and the ones who don't I leave alone.
Working on a cruise ship is a very stresful job. These people generally have to be on duty seven days a week, and for hours every day. They are going to have bad days. While there is no excuse for them being rude, I suggest you give them the benefit of the doubt at least once. If they are just as bad the next day that is a different story, though.