Green’s Dictionary of Slang

tat n.1

[Hind. tat, a strip of coarse canvas, used to make mats or screens; thus as SE, coarse canvas made esp. of jute and used for sacking]

1. (also tatter) an old rag; thus milky tats, white linen.

[UK]H. Brandon Dict. of the Flash or Cant Lang. 168: The paper makers get the tats and never tip the motts a posh, but fence the milky ones with some swag chovey bloak.
[UK]G.M.W. Reynolds Mysteries of London III 66/1: Tim put on the tats yesterday, and went out a durry-nakin on the shallows, gadding the hoof.
[UK]‘Ducange Anglicus’ Vulgar Tongue.
[UK] Hotten Dict. of Modern Sl. etc. 107: Tats old rags; milky tats, white rags.
[UK]Leaves from Diary of Celebrated Burglar 66/1: I wus bro’t up to t’ trade o’ ‘tat-faking,’ that is, maiking awd rags bring their money’s wirth; no matter wethura they’s white tats, woolen tats, or harding’s.
[UK]Sl. Dict. 319: Tats old rags; milky tats, white rags.
[UK]Clarkson & Richardson Police! 347: All the clothes are bundled into a bag, called a ‘tat’ bag, which the thieves take with them. This description of offence is [...] committed about dusk by persons under the guise of rag-gatherers.
[Aus]Bulletin (Sydney) 10 Feb. 24/2: At the close of the ninth round the tatter was aimed heavenwards on his account, which is our new patent way of saying that Fitz. skied the rag, full up to the brim of standing before an opponent who was all legs and wings.

2. anything seen as mediocre, vulgar, rubbishy.

[UK]K. Williams Diaries 30 Apr. 63: Dress rehearsal at Guildford. Tonight at Eight Thirty, appallingly incompetent [...] This is undoubtedly tat of the most menacing order.
[UK]K. Williams Diaries 27 Mar. 171: Blackpool is the end of the line [...] Hateful, tasteless, witless, bleak, boring, dirty tat.
[US]B. Rodgers Queens’ Vernacular 194: tat (Brit gay sl) a white elephant, an eyesore.
[UK]J. Sullivan ‘Christmas Crackers’ Only Fools and Horses [TV script] The Monte Carlo Club. It is all tinsel and tat, the kind of place that looks good with the lights out.
[UK]Observer 11 July 17: Seedy attractions and tired shops flogging tat.
[UK]D. Mitchell Black Swan Green 62: Don’t trust a Jap or the tat he churns out.