How Syrian rebels report chemical attacks on them almost weekly (lately daily): I kid you not.

Here, is one

Charles Lister‏Verified account @Charles_Lister

Replying to @Charles_Lister @washingtonpost

Widespread reports of multiple chlorine bombs dropped on areas of East Ghouta outside #Damascus.

here is another about widespread reports from yesterday: this one is a claim of Napalm and Phosphorous attack:

How come those don't get publicity? How do Western media and government decide which of the weekly claims of chemical attacks by Syrian rebels are believed and which are to be discarded? I am just trying to understand.