Huge Sinful Colors Update (comparisons and changes to the core display at Walgreens)

Since all Sinful Colors and Sinful Shine polishes are on sale this week at Walgreens for $0.99 each (now through 2/22, no coupon required), I thought it was the perfect time for a huge Sinful Colors update. I've received some incredibly helpful info from some of you over the past few weeks, so I'm sharing it all here in one giant post. If you're a Sinful Colors fan, grab a drink, get comfy and