I don't think I used the word "sketchy" till I came to college in Virginia, but now I use it with such frequency (especially whenever a party, a city or nightlife is involved) that I am surprised that the meaning I use most for it is not included in most dictionaries. Is there a way to track the evolution of the word? How recent is it, and what its geographical distribution?
He's talking about sketchy in a sense something like "questionable, iffy, untrustworthy, unsafe, poor quality, creepy, deprecated".
Some examples from the web:
There's an area near the river in town that is really sketchy: a lot of muggings and violence, and naturally lots of graffiti.
The Husband has since talked to some of the doctors who work with him now and they say this doctor and practice is really sketchy. They don't recommend he take the job and worry how it would affect his reputation.
When you have a sketchy driving record like me, and you, just shop around, you have to go with the large outfits as they can absorb higher risk folks.
I don't think its laced with cocaine since the guy dealing to us isn't a sketchy guy lol.
Anyways, I wasn't trying to compare the morals of salesmen with sketchy bankers.
hair is spilitting at the ends and bangs need a trim but dont know where to get a cheap but not sketchy haircut
The word "rise" seems to be attached to really crappy sequels and prequels: Rise of the machines, rise of the lycans, rise of the Cobra, Rise of the silver surfer, Carlito's Way: rise to power. So sketchy.
If any of you ever see me at a show or an event, and I hand you a baked good, it’s really not sketchy. It’s simply because I’m a nice girl.
That was in the early '90s in a sketchy building on the Lower East Side (which was still very sketchy back then and had no boutique hotels or non-dive trendy bars).
My assumption (without real evidence) is that that this usage started with the sense "composed of an outline without much detail" (OED sense 2), and the figurative extension "Of a light, flimsy, unsubstantial or imperfect nature" (OED sense 3), further extended via the phonetic associations of neighbor-words like scummy, scurvy, scruffy, scuzzy, skeevy.
This usage has come up in a few LL posts over the years (e.g. "Sketchballs", 2/18/2006; "Skeevy", 6/22/2009), but we've never tried to track its origin and progress in time and space. It's not easy to do this, because even today, the great majority of uses of sketchy are the more traditional senses.
One way past this problem is to look for particular collocations (like "sketchy guy(s)") that are highly likely to involve the new sense. Tracking this phrase in Google books, we find this from the teen novel Brave New Girl (2001):
He looks like a crazy person, like some sketchy guy you'd see on TV. Actually, more like some stupid actor playing some sketchy guy — too good-looking to actually be sketchy.
And this from Dana Lear, Sex and sexuality: risk and relationships in the age of AIDS (1997):
He learned a year later that she'd been mostly unsafe with her previous partner, who was a fly-by-night, a sketchy guy, a businessman, …
Here's from Betty & Pansy's Severe Queer Review of New York City (1994):
This is where everyone goes when J's (see Cruising, Sex Clubs) kicks you out at 8 a.m. Because it is one of the only bars open in the neighborhood at 8 am, warm, and other sketchy guys are there.
But before 1994, the Google Books trail goes cold for "sketchy guy(s)". Turning to "sketchy street", we find Amanda Anderson, Tainted Souls and Painted Faces: The Rhetoric of Fallenness in Victorian Culture (1993):
Dickens's depictions of Alice Marwood, the sketchy street woman, and Edith Dombey, the commodified wife, reveal how his emergent preoccupations with …
Checking out "sketchy neighborhood", the earliest clear example is in Fodor's Italy '96: On the Loose (published in 1995):
The main drawback is the sketchy neighborhood; women might not want to wander around alone at night.
FWIW, my own memory is that I first heard this usage among students in the early 1990s. So I'd guess that it originated somewhat earlier, perhaps in late 1980s, and then spread through the usual youth-culture channels. I have no idea whether a particular geographical, ethnic, or affinity-group subculture was the source.
But it won't surprise me if Ben Zimmer finds an example in Mark Twain's letters.
[By the way, not all dictionaries are out-of-date with this one. It's not in the OED, AHD, or Encarta, but Merriam-Webster online has
3 : questionable, iffy <got into a sketchy situation> <a sketchy character> ]
[Update -- here's another piece of evidence about the time-course. In the Switchboard corpus (2,400 telephone conversations collected in 1990-1991), there are no instances of sketchy (in either the old or the new meaning). In the Fisher corpus (11,699 conversations collected in 2003), there are 47 instances, all of them involving the new meaning.
So whenever and wherever the new sense originated, it spread through the American population at large during the 1990s. This is consistent with the evidence from Google Books, where it starts showing up in 1994 or so.]
[Update -- it occurs to me that there might be some historical connection with the obsolete slang usage glossed by the OED as "A ridiculous sight, a very amusing person; so hot sketch, a comical or colourful person":
1917 S. LEWIS Job xx. 299 You women cer'nly are a sketch! 1921 H. C. WITWER Leather Pushers x. 269 This Roberts is a hot sketch for a fighter, anyways! 1925 E. HEMINGWAY In Our Time (1926) 84 You're a hot sketch. Who the hell asked you to butt in here? 1926 MAINES & GRANT Wise-Crack Dict. 9/2 He's a sketch, he's comical. 1930 J. DOS PASSOS 42nd Parallel v. 399 ‘He's a hot sketch,’ said one of the girls to the other. 1930 J. B. PRIESTLEY Angel Pavement xi. 604 You do look a sight, Dad... I never saw such a sketch.