you follow the food label. the manufacturers change their labels when they change their recipes and they certainly don't notify sp when they do it. plus, different regions have different recipes and that often means slightly different calorie counts.
also, if the entry has a username beside it that means another person entered the info in. and there are a lot of people on here who are quite bad at data entry if those entries are any indication. add to that that there currently isn't a way to weed out old entries and you have a lot of options that aren't accurate anymore.
so use what is in front of you. it takes a little more time to type in, but you'll have the correct info.
-google first. ask questions later.