(Please note: I wrote this post right before I officially became "in shidduchim")
The Nosy Shadchan, aka the NS, is an interesting character. She is truly trying to help, but she has got no clue how to do that, or even what that means.
She is driven by a combination things. There are horrible feelings over the 'nebach' singles that she knows, that mamish make her heart twist, and there is a desire to do her good deed of the day by redting a shidduch. Oh, and the shadchunis gelt won't hurt either.
See, the problem is, the NS has no concept of boundaries. She doesn't realize that there are some things that can only be said by a girls mother, if at all. And she doesn't realize that, contrary to what she thinks, the world really DOESN'T revolve around her opinions. And so she dispenses them. She believes she is doing a really good deed, because she is giving her opinion free of charge.
What she doesn't realize, is that's the only way she could ever dispense her opinion, because even her own mother, (she should live and be well) wouldn't be willing to pay for pearls of wisdom from the NS:
"mamaleh, who's gonna marry you if you walk around in such shmattehs?"
"zeeskeit, I tell you, you have to be less picky. You aren't getting any younger, you know!"
"so what was wrong with the Gimpelmayer boy? I hear you turned him down too!"
And of course,
"you shouldn't be eating that sheifella, you need to slim down if you want to get the boys to look at you!"
So how to deal with the Nosy Shadchan? Well, assuming you are all out of rubber bands to shoot at her head, or that you aren't willing to commit a homicide over her, the solution is very unsimple. My best advice is to....smile. Just smile. Agree with her. Make her feel like she's done her good deed already, or else she will continue trying to do her good deed, and it will get less and less fun as she attempts further. You also have to beat a hasty retreat, because they don't give up, those NS.
Please realized that the NS is the kind of shadchan I have had the most encounters with, as they are the the ones who are the most likely to run a red light.
It's important to note, that the NS is not only involved in the noble art of redting shidduchim, but they are also very busy trying to aid the shidduch process along. This includes some important, crisis-ending tasks such as trying to persuade people to date each other. ("But zeeskeit, he's such a mentch! What's the big deal if he's three years younger than you? You're nineteen years old already! You aren't getting any younger you know!") And trying to persuade people to give it another shot. ("you know, that was months ago! You've both matured since then!") She also tries to improve your chances for getting married off via other NS. ("I have the perfect diet for you!") And of course, she tries to improve your general state of happiness by reassuring you that there might just be someone out there for you. ("Mamaleh, have I got a boy for you!")
And for the few who have been married off by a NS, all I can say is wow. I've heard you people exist, but I have yet to meet one.
Don't confuse the NS, with the Professional Shadchan, or the PS, or with the Well Meaning Shadchan, or the WMS. They each have their own ups and downs, and any category of shadchanim can turn into the SS, or Successful Shadchan, Be'ezras Hashem.