re: Name a Course that beat you down even though you were playing your best at the time.

I've probably played several dozen major championship courses including a couple that many would consider among the most difficult golf courses in the country, but I do not understand for the life of me how the pros shoot 15 - 20 under every year at Seaside on Sea Island. That course just absolutely eats my shite up even when I am playing well.

River Course at Blackwolf is insanely difficult at least for me when they've got the greens running. Long, no room to miss anywhere, and greens running at 14 or something stupid.

Sneaky entry - Pete Dye course at French Lick will kick your arse even when you're playing well.

You'll see Dubsdread at Cog Hill on some lists like that, and I go the other way on that one. Some tough holes, but I've played not great and still managed to score on that track. Chambers Bay is kinda similar - just a big open ballpark so you can miss it a bit.