"he was accompanied by an unappealing individual"

Could do with more context, but "encachado" means "well-dressed", so I assume mal encachado means badly or scruffily dressed.

From the Oxford Spanish:

3 (arreglado) well-dressed, smart (inglés británico)

encachado, da.

(Del part. de encachar).

1. adj. coloq. Bol. y Chile. Bien presentado, atractivo.

Or "iffy", like HH's "shady", it depends on the level of informality and the target audience/purpose/context.
A UK English version might be "... had a dodgy-looking geezer in tow..." or similar.

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Note added at 3 hrs (2011-08-01 15:03:24 GMT)
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For example The Times (NY or London) or the National Enquirer (or The Sun in UK) wouldn't use the same vocabulary or style.

Another option. Examples: (with a sense of humor):I was seated at my window one morning when a very disreputable-looking person slouched into the room. He was arrayed in a seedy suit, which hung upon his lean frame in bunches with no style worth mentioning. A sheaf of scraggy black hair leaked out of a battered old slouch hat, like stuffing from an ancient Colonial sofa, and an evil-smelling cigar butt, very much frazzled, protruded from the corner of his mouth. He had a very sinister appearance. He was a man I had known around the Nevada mining camps several years before, and his name was Samuel L. Clemens.; www.cliffsnotes.com/.../Ghosts-Summary-and-Analysis-Act... - En cachéThe rain makes the old man even more disreputable looking than usual, and Regina makes it clear she is ashamed of his coarseness and vulgar appearance. ...; books.google.es/books?isbn=1902930010...
Mairi Robinson, Scottish National Dictionary Association - 1999 - Foreign Language Study - 819 páginas
2 of clothes shabby, worn Ial8-19. na scruffy, disreputable-looking person, a rascal 18-el9.