Depends on your
definition:
1. An intense feeling of deep affection
2. A deep romantic or sexual attachment to someone
If you're talking about appreciation and/or enjoying time together -- I suspect a very high percentage, from both sides.
If you're talking about affection and non-sexual attraction (since you said not "lust") -- I suspect a high percentage of regulars but much lower for someone you've seen only a time or two; overall, probably not a majority but still a fairly good percentage, from both sides.
And if you strictly apply the qualifiers
intense and
deep, as I would -- I suspect in most cases it's no more than 2% or 3%. It's hard to develop that intensity,
for aspects of the relationship other than sex, with limited time together.
I assume most ladies I see really do appreciate me as a client and enjoy our time together (as I appreciate/enjoy them). and I assume several feel
some degree of affection and non-sexual attraction (as I feel for them). If they want to characterize that as "love," fine. I don't, but it's a matter of semantics. There have been a couple of ladies for whom I might use that word for my feelings, although not intense and deep to the point of divorce and seeking a more permanent, civilian relationship with the lady. And I seriously doubt whether any of the ladies I've seen strongly yearn for a more permanent, civilian relationship with me. But that's OK; appreciation and some degree of affection are plenty, aren't they?