In most cases, slugs are neither a good nor a bad sign - they are just slugs. Slugs can really chew up Hosta, however, so if you have it, you should deal with them. The easiest way is to find the places where they hide during the day to protect themselves from the heat of the sun. Slates and other flat surfaces laying horizontally are a favorite place for slugs. Slug control pellets can be a bad thing - often the poison is deadly to birds. While a little on the gross side, a shallow plate with a bit of beer poured in it pushed into the soil so they can get to it attracts them in the evening - just scoop them out and discard them when you think of it.