I would think that Carnoustie is the nearest thing to the test of the 5 handicap wannabe. Everything going well, until the 16th onward.
Bob
I'm a 5 handicap (probably closer to 6 right now) and my lifetime total on two rounds over the last three holes at Carnoustie is -2. I've never found Carnoustie to be as awfully difficult as most people believe it to be. I've had a far more difficult time with Prestwick. Lots of people consider Turnberry a stern test and TOC easy, I've shot 77 both trips to Turnberry, in the 80s both times at TOC.
I suppose its down to the usual where everyone's game is a bit different, but for me the main things that will really kill me are:
1) big penalties for missing the fairway - water or OB obviously, as well as trees which don't leave you with a shot at or near the green, or rough that's so bad you can't even play for the green from wedge distance.
2) approach shots with the ball below my feet, especially with short irons/wedges (but I'm damn good with the ball above my feet, go figure)
3) narrow (as opposed to shallow) greens
4) closely mown areas around the greens (as opposed to thick rough) Since I've always played courses with thick rough around the greens I've become fairly proficient at the flop shot, so a scratch player with a more well rounded short game would have a great advantage against my more one dimensional short game when more options for a given shot are available versus just surrounding the greens with spinach.
Personally I'd lean more towards the short but tricky/tight layouts with small greens that were mentioned, like Olympic Lake, as being something that a scratch would want to play me on if he wanted to truly humiliate me. Pinehurst #2 would be another one, even though the greens aren't narrow per se they play narrow, and a guy who is really good at the bump and run around the greens would eat me alive even if we missed the same number of greens.
Give me a course that's more defended by length and tricky greens like Oakmont and if I have a good ball striking day and if the scratch is off a bit or I'm getting a few more than usual in the fairway and have a decent feel on the greens the humiliation could go the other way.