litter box odors

The NA-50s arrived, very pleased, particularly as they're nearly silent, and the one in the bathroom really does knock out litter box odor (3 boxes). The reason I bought them (and may be buying more) is to deter cats from spraying in the house — having tried everything else to no avail. The 2nd unit is next to a small table that's been sprayed daily for over a year, unknown why - clean it daily, have tried pheromones, No-Mark, herbs, etc. In the 5 days the NA-50 has been there, table has been sprayed once, an improvement, but must monitor for weeks/months before declaring it a success. If this is the answer (perhaps removing odors offensive to cats, which prompt them to spray), it's a Godsend to cat people. I'll keep you posted.