FWIW theSkimm isn't outright spam - they're a fairly popular super-short newsletter that I think does a mix of world news and lifestyle / culture stuff, apparently marketed at women. I subscribe to Finimize (financial news) and Casual Spectator (sports), and theSkimm is often referenced as a similar newsletter.

Not to diminish the annoyance of being on surprise email lists. I agree it's frustrating, and it sounds like Scott's Cheap Flights should have been more clear with their users about the price of their contests.