Occasionally I'll write letters of complaints (come on, how many experiences are truly awful vs just small inconveniences - if you intend to answer that, please start another thread

). It takes a lot for me to write a complaint letter, and when I do it's deserved.
But I also believe that fair is fair. If I'm willing to complain, I should also be willing to compliment - especially when it's deserved.
I don't rely on karma in those instances, btw, or verbals. I put it in writing & address it to the vp-personnel, station and/or fa manager, etc, etc, so it gets documented & put in the employee's file. 2 reasons - one, they should be recognized when they 'done good' & by doing so, it will encourage them to keep 'doing good'.
Cheers.