Normal people seem to be happy with a 5 star ranking system for, well, just about everything! I've stated on many occasions that is not flexible or accurate enough which is why I use my special base-10 system with detailed rationale. It does occur to me however that there is a cross-over with the 5 star approach, especially when it comes to the Comedy side of the Fringe. You see it would be very difficult to get a show that would get less than 5/10 - the financial backers would not let this happen. Yes, outside of comedy this is very possible and of course during the EIFF it's happened a few times.
Here's how the ranking systems cross-over:
1 star = 5 points (walk out if you mistakenly end up in there);
2 stars = 6 points (if it's free and you need to waste an hour);
3 stars = 7 points (okay if you're a big fan and/or cheap tickets);
4 stars = 8 points (very good and worth full price, recommend to others);
5 stars = 9 points (excellent, beg other people to go and see it!);
+ stars = 10 points (perfection, pay for your friends to go and see it).
You can see the benefit of having an extra level to differentiate the class of 5 stars. There are shows last year that were grouped together that actually dragged down the ranking of, for example, Rhod Gilbert and Sammy J by only giving them 5 stars and not 6!
The bottom half of the scale is the mirror image (or evil twin) of the top half, i.e. 5 points being if it's free and you have time to kill don't go and see it (or walk out). The remaining ones are:
4 points = Even if you are in desperate need of something to do ... don't!
3 points = Very bad in all areas. You would fall out with a friend over them making you watch this.
2 points = You'll actually hate yourself for sitting through this, it's that bad.
1 point = You wish bad things on the creators so they can never produce such an abomination again.
And for completeness sake, here are some films that plumbed those depths:
5 points = Scary Movie 2
4 points = Armageddon
3 points = Process (2004)
2 points = Anatomy of Hell
1 point = Ecsatsy of Robert Carmichael