Accuracy of exercise calories?

NotASoul

I log my exercise fairly accurately, and the site frequently tells me to add 300-500 calories to my daily allowance. I tend to take this with a pinch of salt and take it to mean that it won't hurt me to go over the original goal by a little, but don't tend to aim for the new (higher) amount as such.
Was wondering whether the additional calories it says I should eat are accurate and whether it's a suggestion or a goal? My usual allowance (ignoring exercise) is 1200 - should I follow the site's suggestions to eat more when I exercise or just ignore them?

Iknowsaur

MFP is notorious for overestimating calorie burns.
That being said, people generally (from my experience) eat back 20% to 50% of their "earned" exercise calories.

sbarella

http://www.shouldieatmyexercisecalories.com/

EDIT: damn, domain expired

http://www.myfitnesspal.com/topics/show/1096845-eating-back-exercise-calories