Back when I perused the Personals frequently, I saw a phrase that never made much sense to me, and put me right off: “Looking for a partner in crime.” I never got the appeal of this phrase, and it always struck me as faintly distasteful. Obviously, these women (I never read men’s ads, but it must be even more distasteful there) were playing around with the concept of “looking for a partner,” which seems redundant to the posting of a personal ad in the first place. Equally obvious (I’d hope) these women weren’t being literal, but what does the figurative meaning denote? That she considers herself somewhat naughty? That she wants someone she can trust with her secrets? That she has a very lame sense of humor? That’s she’s desperately stuck for something meaningful to say about what she’s looking for? Can anyone make this expression make any sense to me?
She sounds like fun.
ETA: not sure how to explain “fun”.
If I used it on a dating site, it would mean I was looking for someone to do things with, either sane and planned or zany and spur of the moment. Someone who wouldn’t just tag along as support, but be actively involved in interesting things.
I also see it as a fun thing, not a weird or creepy thing.
My first instinct would have been that she’s married, looking for a married partner. It would be a code phrase.
That is, for classified ads, where that’s basically the entire ad. In an online ad, where you can freely reveal that you’re married, I just imagine someone who is playing up a sort of Harley Quinn theme. Or just the generic bad girl theme before Harley was so big.
But then, as I think about it, it’s probably just some kinda bored woman who is thinks it’s funny. She wouldn’t be all that different from anyone else.
Just call me the Tumbling Dice.
‘Cause all you women is low down gamblers
Cheatin’ like I don’t know how
Baby, got no flavor, fever in the funk house now
This low down bitchin’ got my poor feet a itchin’
Don’t you know you know the duece is still wild
Honey, got no money
I’m all sixes and sevens and nines
Say now baby, I’m the rank outsider
You can be my partner in crime
`Jagger/RichardsOP is overthinking it. The term “partner in crime” is just a reference to having a close friend, confidant, someone you can share secrets with, etc. The term crime is not to be taken literally, or intended to mean anything illicit or adulterous.
I have used this term and heard it frequently among friends when referring to various relationships.
Just as an aside: I’m enjoying the overlay of your avatar with your comments. 
Is this directed at me? If so, glad you enjoy.
As to Omar Little’s point: I tossed out “someone you can share secrets with” in the OP. It’s still dumb. One of the elemental things about “partners in crime” is that’s who’s going to give you up to the cops whenever he gets caught. The last thing I’d want in a confidant–someone who has the goods on me, and can use them as a bargaining chip to keep his ass out of jail.
I know the ‘reply’ system in Discourse is confusing, but I replied directly to Omar Little’s post. My comment was not directed to you. I can understand the confusion, though.
This. But I’d add it’s meant to convey a slight bit of naughtiness. Like maybe we’ll go skinny-dipping in the lake at midnight together. Not we’ll rob banks together.
Also, holy shit is (maybe was? It’s been a while for me) this overused in personal ads. It’s not quite “long walks on the beach” but it’s “I’m equally comfortable in jeans and sneakers as in a fancy dress” level of cliché.
“Let’s be mildly transgressive together because I’m a fun person”.
Which was probably “take off my shoes and walk in the fountain” levels of social transgression.
Still used all over the place. That’s sort of my point here. It’s a total cliche, it’s cutesy as hell, it might mean anything from “Let’s scam people together” to “Let’s hold hands in PDA-forbidden areas” and it’s sorta dumb.
To broaden the OP out a bit, it’s amazing to me how much people give away unwittingly in their personal ads and profiles. I’m a little persnickety about literacy, for example, and am ever astonished at people’s inability to write a paragraph without sixteen typos, letting me conclude “No, I’ll never get along with her.”
You’re misthinking this, the only person I’d plan my hypothetical crime with is someone I’d trust enough to not dime me out.
The ‘crimes’ I’ve committed with my gf / partner-in-crime include going to/being in the park after sunset & playing in a fountain. 
…hardly 20-to-life felonies.
No. It never means that. Not sure why you’re hung up on a literal reading of a colloquialism.
… we can just stop here.
Discussions like this were what made the now-defunct forums on Plenty of Fish the only worthwhile use for the site.
Maybe a little clarification is needed from the OP. Were you perusing them for entertainment purposes, looking for the humor in just reading them, etc. or where you seriously looking for someone to meet up with? If the latter, then you are free to use whatever criteria to judge their merit and suitability for you as a potential date. But you shouldn’t expect everyone else to have the same likes / dislikes as you.
I used to work with a guy I referred to as my “partner in crime”. We were both teachers at the same school, the heads of our departments, and we worked together closely on lots of projects that were of our own initiative, like restructuring our recruiting process, or revamping standardized test prep. We basically both sorta straddled the line between teachers and assistant principals, and we had a shared vision (along with our principal). What we really were was partners, in the professional sense, but that word has a world of messy connotations that didn’t apply: we were neither romantic partners, nor legal partners in the sense of business ownership.
I dislike the expression “work husband”, so I either called him my “work BFF” or my “partner in crime at work”.
It sounds to me like an excellent phrase to use in a personal ad: The sort of person they’re looking for is the sort who would understand what they mean. You’re vaguely turned off by it: All well and good, if you’re not the sort of person they’re interested in.
No, I WANT women to expose their obnoxious qualities: illiteracy, religious fanaticism, Trumpism, drug addiction, etc. A woman uses “partner in crime,” and I conclude that she lacks the wit to express herself clearly, doesn’t know a cliche from a hole in her ass, is probably mildly transgressive in ways that don’t interest me, is a nudnik, probably watches too much reality TV for me taste.