Yes, you can. Running them without cleaning them will glaze the drums, and lead to squeaky brakes. The boiling temperture of DOT 3 fluid is about 230 degrees F, Dot 4 is about 265, so it would take a lot of heat to get the fluid out of them. However, both types are water soluble. So wash them down with water, then gently heat them with a torch. The heat will draw the brake fluid to the surface so it can be washed away. Do this 4-5 times, you should be ok. Then lightly sand them. If you are using DOT 5 fluid, replace the shoes. It has a very high boiling point, and is silicone based, so is not water soluble.

Just in case anyone disputes this info, it came from Motor magazine, an industry publication, in an article titled "silver bullets", a compilation of tips sent in by professional who use these methods.