sketchy friends

John Grishamの短編小説集Ford Countyの中のFish Filesを読んでいます。主人公はFord Countyの余り儲からない田舎弁護士。未解決案件の一つでゴミ屑状態（Fish Files）であったチェインソー事故の案件の相手メーカーが欧州のメーカーに買収されたことにより、相手側の弁護士から突然金儲けになりそうな提案が出てきました。
The truth was, he had not been able to locate either Travis Johnson or Doug Jumper. Travis was rumored to be out west driving a truck, something he evidently could do with only seven fulllength fingers. Travis had an ex-wife with a house full of kids and a ledger full of unpaid childsupport. She worked a night shift in a convenience store in Clanton, and had few words for Mack. She remembered his promises to collect some money when Travis lost part of three fingers. According to some sketchy friends, Travis had fled a year earlier and had no plans to return to Ford County.
弁護士Mackの顧客が事故で怪我をしたTravisとDougで、そのTravisの "sketchy friends" とはどんな友人でしょうか？　 "sketchy" の意味を辞書で調べます。
・Oxford English Dictionary: Dishonest or disreputable: once the story does come out, the fact that you tried to hide it will seem sketchy: a sketchy neighborhood
・Cambridge English Dictionary: containing few details: So far we only have sketchy information about what caused the explosion.
・Vocabulary.com: Something sketchy is incomplete: it includes the major points but lacks detail. If a political candidate avoids going into detail about her political views, you might say her platform is sketchy.
A sketch is a quick drawing that doesn't have a lot of detail. That definition should help you remember that sketchy things are incomplete. A sketchy speech from the President will outline some important ideas but be short on specifics. A sketchy plan for the weekend would be "Let's go out to eat." That's sketchy because it has the general idea but no specifics, such as the time or place.
スケッチが大雑把な絵の描き方との認識はありましたが、"sketchy" が人を含め色々な事の形容詞として使えるのは知りませんでした。