Makeup matron is off-color

Tracey Ullman, the woman of a thousand faces, pares the crowd down to essentially one tonight in her intermittently entertaining HBO special “Trailer Tales” (8 p.m.).

The Emmy-winning actress and comedian single-handedly kept the latex industry afloat in the mid-’90s while using all manner of masks and prosthetics to bring her wacky cast of characters to life on the “Tracey Takes On” series and several specials for the cable outfit. One of her most popular alter egos, chain-smoking, trash-talking makeup artist to the stars Ruby Romaine, takes center stage tonight, although a couple of other characters make cameo appearances.

With her own time in the makeup chair scaled back, Ullman steps up her involvement in other areas of the hourlong production, directing and co-writing the program while sharing executive producer duties with Allan McKeown.

Ullman has also signed up a stable of guest stars, including Debbie Reynolds, M. Emmet Walsh, Paul Dooley and Barbara Bain, to help flesh out the thin-feeling story of Romaine’s bid to get her movie studio job back after an ill-advised stab at retirement.

Most of the action unfolds in flashback as the makeup matron spells out her plight to Reynolds while working on the star’s ever-beaming face. Wearing pointy silver glasses and a wig that looks like a pile of whipped-up lemon meringue, Ullman has this tart-tongued character down cold, but the humor that’s supposed to flow from Romaine’s bull-in-a-china-shop offensives comes off as offensive on occasion and accompanies some queasily unpleasant scenes elsewhere.

Romaine’s attempt to get some nonunion work on the set of a gross-out reality show generates laughs (“You don’t need a makeup artist; you need a janitor”), but then there’s the strangely ugly scene in which Romaine and her married lover, discovered in the throes of passion by the man’s young son, scream jeering insults at the sobbing lad until he wets himself. Later, a passing reference by Reynolds to daughter Carrie Fisher’s bipolar disorder seems likewise pulled out of some other show.

In such moments, the comedy is disguised too heavily for the show’s own good.