My experience with the "importance" slider.

Oh, yes. Flexible matching. One of eHarmony's most recent inventions. Where they temporarily ignore the preferences you've expressed about smoking, drinking, religion, age, or location.

Thankfully, they haven't gone to "flexible matching" on gender. Yet.

Sure, you can always close anyone for any reason that you see fit. But it's still a pain to weed out the matches that you've already said that you don't want.

You do have one weapon against the "flexible match". The preference slider. Where you have a chance to point out how "important" these are, from a scale of "very important" to "not important".

And, yes, I've had to use it. Here's my experience.

Geography
My net was cast pretty wide - I've accepted matches from my state, and every state surrounding me. (I don't necessarily accept matches from all of these locations, but it's the best filter for my purposes.) Unfortunately, "flexible matches" from outside this radius were the most difficult to get rid of.

In my experience, my box was flooded with matches far, far away until I moved my "importance slider" to the next-to highest setting. And when I did that, I received no more at all.

Strange. But that's my experience, anyway.

Age
I'm in my late 30s, and set my age preference for to my age or below. (I'm not ready to cut off the possibility of having children, and want to spend a decent amount of time getting to know a woman before making the leap.) And, yes, the "flexible matches" have almost all been older than my preference. (Not all of them, though.)

For me, the "midway point" has worked pretty well. About 1 in 10 will be above my stated age preference, and then by a maximum of 5 years. (Not counting the ones who lie about their age.) And, for me, this has been a decent screening point.

But if you get more matches than me, even this much manual screening might be a pain. In that case, go higher.

As for the rest - I don't have much experience. I've never wanted to eliminate social drinkers or smokers. They're set at lowest "not important", figuring I'd manually prune the heavy drinkers or ones that smoke at places other than parties (even that last one's annoying, but not deal-killing alone). For me, religion matching has been a primary reason for using eHarmony, so it's always been set at the highest level. And the other stuff, alone, isn't a deal-breaker. (My income is fine, and I'm fine with meeting intelligent and fun women even if they've been educated in the school of hard knocks.)

Got different experiences? Let's share here, or in the google group.