One who nitpicks (finds fault in unimportant details).(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "nitpicker" in a sentence
""The ad sounds convincing -- but perhaps being a word nitpicker, the Sun does now 'might not mean much if Sun has drastically cut back due to plummeting sales," Rich Partridge, an analyst at Ideas International, said in an e-mail."
"Candy: My review process: I read the book, dog-ear any pages with problematic passages, do research as necessary to make sure I’m not talking entirely out of my ass when I’m in nitpicker mode, then write."
"DonBelacquaDelPurgatorio on Corruption and popcorn nitpicker on A get together to tear it apart"