Can you trust what you find in Google Scholar (and other online databases)?
An article published in Nature on Monday, February 24, 2014, "Publishers withdraw more than 120 gibberish papers", reveals that publishers Springer and IEEE (Institute of Electrical and Electronics Engineers) have withdrawn 120 papers from their online databases after Cyril Labbé exposed duplicate or computer generated articles found in Springer and IEEEs databases. Labbé's article "Duplicate and fake publications in scientific literature: how many SCIgen papers in computer science?" (94 Scientometrics No. 1, 329-396 (January 2013)) exposes the ease with which fake articles make their way into online databases and into citation chains.
Can you trust Google Scholar? Probably. One lesson we can take away from Labbé's experiment? Exercise care and a modicum of skepticism when using online resources.