1. Jordan Catalano 
Mysterious, floppy-haired, droopy-jeaned, an excellent leaner, Jordan Catalano of My So-Called Life is the archetypal irresistible slacker bad boy of your dreams. He seems perfect because (besides being beautiful) he is quiet and deep, soulful, full of longing. He plays guitar, wears vintage/thrift store clothes (or is he poor?! Sad puppy!) and he can’t read. It is clearly your duty/destiny to keep his tender secrets, make out with him whilst touching his greasy locks and make sure he graduates high school.
Why he’s bad: his mystery may just be emptiness. He won’t hold hands with you in the light of day (let alone in front of Tino). Once the poetic mid-smooch mumblings are gone, what will you have left to talk about? Girlfriend, Catalanos must roam free in the angsty wilderness. If you love him, let him go.
See also: Lane, Trent (Daria)
2. Daniel Desario 
Foxy, easygoing, carefree, Daniel Desario of Freaks and Geeks fame is a freak of hottie proportions. Lanky and loveable, he shoots sweet smirks in your direction across the cafeteria table he non-chalantly invited you to sit at. He stays out late, drives a sweet car, skips class and here’s the sexy part—he always asks you along! This must mean that he loves you! Why would he be so nice, so flirty, so easy and unimaginably cool?! He’s not like your last crush, Jordan, at all!
Why he’s bad: he’s a total high school con man—a grifter in a leather jacket. Sure he thinks you’re an okay chick and all (for a brainy square, you’re kinda cute) but he mostly wants you for your homework, your excellent house party digs and whatever fleeting entertainment you can provide. This kid has acting chops that will get him through life. As adorable as he is playing D&D with your little brother, Desarios can’t be trusted.
See also: Sawyer (LOST)
3. David Letterman 
Okay, so he’s not the most classically beauteous of the bunch, but as far as bad boys go, he’s got the attractive attitude down pat. Let’s face it, funny is sexy and Dave’s got funny in spades. And this isn’t your run-of-the-mill humor either, this is mean, satirical, wry, jerky, weird and intellectually inane stuff. There’s something refreshing about a television figure who doesn’t pander to his guests (take a cue Jay Leno). If Dave respects you, you know you’ve earned it; if he doesn’t, he will verbally eviscerate you on camera then re-air the footage ad nauseum. Uber private and hermit-like, he’s got the secretive thing going like the dudes above, he loves his mama and he’s fiercely smart. What’s not to like?
Why he’s bad: Um, commitment issues like whoa. It’s all well and good to not be the marrying kind, but don’t cheat on your looong time girlfriend, the mother of your child, with each and every broad who works in the CBS studios. The snark is attractive, but boys like Dave use that crap to keep people at a distance. I don’t care if you get the urge, do not hop on his desk and show him your boobies. He won’t show you much in return.
See also David, Larry
4. Alex Karev
Not McDreamy or McSteamy, Alex Karev’s nickname is “Evil Spawn.” Sounds hot and unavailable already, am I right, ladies?! So, this Grey’s Anatomy guy is a total ass. He’ll walk all over you, steal your surgeries and then laugh in your face about it. But then, then! You catch him whispering lullabies to a preemie in critical condition and your heart melts like so many hospital cafeteria pats of butter. He had a rough family life, a mentally ill mother, an abusive father, of course he had to be rough and scratch his way to the top. Of course, he’s all dark and twisty and sexilicious. Following Freud to a t, he tends to fall hard for crazy girls. You’re a crazy girl! You understand why he acts out, why he is how he is. It’s a match made in Mercy Grace heaven!
Why he’s bad: He sleeps with everyone and he’s not just a little damaged, he’s got serious problems. Good guy over all? Yes. But he fights hard and dirty to protect himself, and you don’t deserve that abuse. Let him work on himself for a while. Re-visit after he’s had some therapy. Maybe when he’s head of pediatrics. Until then, avoid running into him in closets, sleeping quarters, or empty rooms of any kind.
File along with Spike (Buffy the Vampire Slayer, Angel) and Logan (Veronica Mars)
5. Don Draper 
The Big Kahuna. Mad Men’s Don Draper is the Everest of bad boys. You know, you climb on because it’s just majestically there. Wow, I’m dirty. Anywho, he’s gorgeous, sleek, dressed oh-so-finely. Oozing confidence, one flick of his cigarette says, “even I would fuck me.” On top of this already selling attitude, he has the magical Desario effect of feigning rapt interest in you along with a little softness, a quiet dreamy impenetrable depth. He thinks aloud; he lets you see his creativity burst forth so you think you’ve witnessed a little miracle. He says All. The. Right. Things. He’s a hot commodity and you’re buying it.
Why he’s bad: come on, anything that lovely can’t be real. He’s a lie wrapped in an enigma, wrapped in five more lies. Go ahead and sleep with him if you must, but know that you’re just buying a ticket to the Don Draper experience. I repeat, DO NOT MARRY. He is for amusement purposes only. Men like Don, if that is his real name (it’s not) get around. If you are not the kind of 60s gal who can self-assuredly buy and use prophylactics, then I suggest you stay home with your Sears and Roebuck massager.
May be filed with the likes of John a.k.a. Mr. Big (Sex and the City)