My kettle was really bad for doing that, and (of course) the water that it dribbled was boiling, so I took action to remedy it before I scalded myself! It turned out that the design was really stupid. The designer had put a mesh filter in the spout, presumably for people who live in hard water areas, to stop limescale getting out. It just messed up the water flow. I live in a soft water area anyway, so I binned the filter but that only half fixed the problem. There was still a big plastic flange in the way so I took a pair of cutters, hacked away at it, and removed it. The problem is reduced by over 90% and most of the time now I don't get any dribbles from the spout at all, really only if I try to pour too quickly.