The recipient proves clearly and specifically what he or she has done right. The reward is of value. Management had to exert some effort to get information and had to find something meaningful. The reward is done with fun, creativity, even joy, and surprises. Praise is not combined with criticism.
Tangible reinforcement proves sincerity.
Put your money where your mouth is. Start slow if you feel this is too ambitious. Perhaps you could just notice who is improving on reports or increasing calls. Make a phone call, write a note, or fax a happy face. You'll enjoy your job more as you concentrate on appreciating your salespeople's success.