I've read a lot of reviews on sites like photozone.de, the-digital-picture.com and the likes and found that quite a few of their review samples turn out to be defective (including the premium 'L' lenses!) and they end up using as many as 4-5 lenses before getting a proper one. This makes me pretty paranoid when shopping for lenses.
I do understand that the higher defect rate on review sites could be due to the use of pre-production samples and\or initial production lots. Also, customer lens reviews on sites like Amazon seem to have lower defect rates. However, this could be due to general customers not being equipped to evaluate lens defects the way dedicated review sites can.
Is there any way to find out the reliability of a lens, and are there any defect rate or reliability charts for lenses? This is mainly to avoid known buggy lenses\production batches.