Here's the scam:

Every winter electric rates go up. Every summer they go down. Rates (in this area of New England anyway) are
set every 6 months. The winter rates go up because of limits to natural gas pipeline capacity during the peak months.

Every winter, after the rates go up and everybody gets their first winter bill, alternative electric suppliers start calling and flooding your mailbox to offer you a lower 12-month rate than the 6-month rate you just became aware of. They don't mention that the 12-month average rate from your current supplier is not much different, and may be less, than theirs.