For more general keywords (widgets), running on broad can be good if you can capture the actual search queries used that result in clicks & sales and then refine your campaign based on that. After the reseach phase build out the keyword list with more specific terms and match the keywords to the most specific landing pages possible. After that, I'd put "widgets" on exact match and send that trafic to the broadest widget category page you have. Chances are when someone types in widgets, they don't really know what they want and are just looking for a nice selection to browse through.
If you run really general terms on broad match, chances are your ad will be showing for more specific queries that may not match your landing page at all. You probably have better landing pages for the more specific varations that will trigger your ad.