By Nancy Lewis Thursday, July 22, 2004 Ma's Kettle looks as if it should have great barbecue. The small-town cafe is housed in a small shingle-covered building not far from Savage Mill. There are no more than a dozen tables, but at lunch (the only meal served except for Saturday breakfast) the cafe is often filled to standing room only with a diverse array of customers, including construction workers, ambulance drivers and politicians. Ma's Kettle also cooks up the food for many of the performers at Merriweather Post Pavilion. I'm not a fan of the barbecue ($35 a half-gallon or $5.25 for a sandwich), though it's the house specialty. The pulled pork tastes like old pot roast, cooked until the taste is gone, then dressed up with a too-sweet sauce that can't camouflage the shortcomings. The ribs ($15.95 for a rack) are just as overcooked, drowned in that same sauce. On the other hand, the potato salad is grand, with chunks of well-cooked potato, augmented by celery pieces large enough to recognize and big pieces of egg in a mayonnaise dressing with just the right amount of vinegar. And the coleslaw is just as good, chopped fine but with a nice sweet-sour bite.