While readers of this blog will know that I am strongly critical of Roman Catholic theology, I will be the very first to admit that there is a lot of stupidity out there critical of Catholicism (the works of Jack Chick is a prime example). Sadly, many Latter-day Saints accept hook, line, and sinker many of these more wacky "arguments" (probably due to the poorly researched works on the Apostasy, such as the dated and poorly-researched book by James Talmage, The Great Apostasy).
Here are links to refutations of some of the wackier elements out there against roman Catholicism:
'Hunt'-ing the Whore of Babylon by Jimmy Akin
Nimrod, Babylon, and the Black Pope by Dave Burke (a Christadelphian)
Phil Porvaznik's refutation of Dave Hunt's sensationalistic nonsense