well it depends... if you fade JC's offshore locks you would be around 24-1-0 which is 97.6%
If you follow a really solid capper you would get 60%-65% at the most and thats really a stretch
It's not just JC, although he's the recent Posterboy for the phenomenon.
Here's my Very Unscientific Guidelines:
If someone posts something as a "LOCK!!!!" All Caps and at least one Exclamation point, it'll lose 95% of the time. Just all CAPS, 90% loss rate. Just a Lock in non caps with Exclamation points, 85% loss rate, and Just Lock with no exclamation points, 80% loss rate.
A Brock Landers Rubber Band play is 100% losers. If you find those, you're set for life.