Slug traps - Any good?

I have a couple of different slug traps loaded with creamy pints of Tesco value bitter. They protect my lettuces, runner beans and my sunflowers. Two of them have a single pot and one has three wells within a larger covered area (attractive because it offers a chance to test 3 different beers side by side, but that is another story). Which trap will catch the most slugs? WATCH THIS SPACE....