Customers can go away with a poor impression if just one member of the service team lets the side down. It is vital for everyone to be at a similar level and standard of service otherwise the combined efforts are for nothing.
If you do have a staff member that is noted for letting the side down, the options are simple... Improve them , or move them.
"One hundred minus one can't be ninety-nine in the hotel business. It may be zero. If one employee out of hundreds gives a bad impression to a certain customer, it will be one hundred percent damage for our hotel image for that customer."
- Ichiro Inumaru ( Japanese renowned hotelier)