Don't hit on the nursing staff

I've been a nurse for almost five years now. And in the course of doing my job, I've been kicked, punched, sworn at, spit on, vomited on, and hit on more times than I can count. The last one is particularly difficult to deal with. I realize that one of the hazards of being a woman is that some men make rude remarks.
Nursing seems to amplify this tendency. There's something about the intensely personal nature of the work a nurse does (asking intrusive questions, feeding people, administering medication, wiping backsides, educating people, etc.) that leads some men to over-estimate their own attractiveness (Now that you've told me all about your genital warts, what makes you think I'd like to date you?) and under-estimate my proffessionalism. (Dr. Grumpy tells a hillarious story about this here.)
I used to work for the VA, which has an overwhelmingly male patient population. And the patients who hit on me there fell into three distinct categories: (1) elderly men with dementia, (2)middle-aged to elderly men who thought they were being flattering, (3) and thirtysomething alcoholics going through withdrawl.
And I soon found that three different responses were required for these groups of people: (1) "Dave, I can't go to the movies with you, but do you want to watch sports right now?" (2) "It's nice to see you too, Dave." and (3) "Here's your pills, Dave."
Most of my current patients are very appropriate. However, there's always those few... Throw in a history of mild mental retardation and some organic brain damage caused by years of drug abuse on top of their usual mental health sypmtoms, and I often find myself grasping for an appropriate response.
The first thing "Dave" said to me when he saw me last week was "You've got a real nice shape--I like you!"
What do you say to that? I know he's trying to be nice (even by the most liberal of interpretations, Dave has never been playing with a full deck) and I don't want to hurt his feelings, but I do want to set reasonable limits for his behavior. So I settled for "I like you too! I'm so glad you showed up for your appointment today."