Is there anything worse than a slow, muddled, badly lit cop movie? Yes: a slow, muddled, badly lit lady-cop movie. (You get the clichés plus ersatz feminism.) In the insultingly shoddy Impulse, Theresa Russell she of the ripe smirk and earnest-little-girl doe eyes plays an underccver vice cop who, for reasons that have absolutely nothing to do with selling the picture, keeps donning rear-zipper miniskirts in order to catch a drug dealer. Russell once seemed a promising actress (she made a fascinating modern temptress in Bad Timing/A Sensual Obsession), but in Impulse she's set up as both a sexpot victim and an avenging Dirty Harriet. The two pulp poses undercut each other, and Russell ends up looking ridiculous all because she can't pout and sneer at the same time.