I have been known to make the odd smart-arse comment. You can get away with it, depending on the clientele. There is one job we work regularly where I've got away with
"Ladies and gentleman, please do be aware that this is a very busy service. If you are currently sat next to your bag, coat, laptop etc, please be aware that there are many people standing on this service. Move your item and allow them to sit next to you. It's possible you may even get along. Most of the people on this service look fairly normal, and I don't believe you will be bitten or dribbled on by the stranger that may sit next to you. However, if you are bitten or dribbled on, please let me know, and the appropriate action will be taken"
Also got away with
"This service is now arriving at XX. Please do be aware that to travel to XX, you need to be sat in the front part of the train. You do have my deepest sympathy if you're travelling to XX, however you do need to be sat in the front part of this service, as it does now divide on arrival at XX."
Also
"Now approaching Coventry. Change here to travel to such exotic locations as Banbury, Leamington Spa, and services to the Costa del South......."
And
"Now approaching XX where this service will terminate. Please ensure you take all personal belongings with you, including children. Any children left on this train will be given an Espresso and a puppy."
It's not often you get told off - my TOC likes us to show our personality, allegedly. I did get told off for the deepest sympathy bit - but one of the big-wigs was on the service, and it was a peak time service full of commuters - plus I was still with my trainer as I hadn't passed out!!!