Cat farts are one thing, but......

I haven't enjoyed the company of a cat inside my house since Rosie passed away, but I have many well-mannered cats and dogs that frequent my porch to bask in the sun and receive many hugs, pats, and praise from me. These are my company when I'm outside, my "porchpals" as I call them. I never feed them because I wouldn't want other people feeding my pets if I had any. I've never noticed any foul odors emanating from these animals while enjoying their company, however, there is this phantom, Old Tom, that leaves his calling card on my front door when the other female cats are in heat. Geeze! does that stink when the sun bakes on it. I have tried everything from Urine-Kleen to new paint to eradicate the smell and have been fairly successful, but that does not discourage Old Tom from marking his territory on a regular basis. As soon as he senses that I have erased the smell, he sneaks back and reestablishes his claim on my porch. I have had several heart to heart talks with Old Tom about the problem, but he says he forgets. Anyone know any cat psychology or have any humane ideas for discouraging this kind of behavior? I enjoy his company too, so I don't want him to feel unwelcome. Pew!

wdyat12