Place first 4 ingredients into a blender or food processor and purée until smooth or desired consistency.
Layer bean dip on bottom of a pie plate, followed by a thin layer of salsa, then guacamole.
Place sour cream (adding a little water if too thick) in a small plastic zip bag, squeeze to the corner of the bag and twist the bag like a pastry bag. Use scissors to cut off an 1/8-1/4 inch tip of one corner of the bag. Use as a piping bag for the spider web design.
Pipe sour cream into a spider web design on top of the dip. Cut 1 olive into "legs" and add black olive "spiders" for garnish.