Content in, at least, the description field are not being correctly encoded for XML. HTML entities such as right-single-quote (’) are being passed through without encoding. These entities are not defined in XML, so validating parsers will reject the file and fail to load the feed (e.g. Doggcatcher on Android, which uses the Expat XML parser)
An example in the current bombcast feed at http://www.giantbomb.com/podcast-xml/giant-bombcast/ is line 42, column 200. The description for "Giant Bombcast 02-12-2013" (GUID 1600-379) contains an illegal rsquo entity.