I think Calflu is right to say we hear immediately about any flaws or perceived flaws in Chanel products, while perhaps praise of good quality is expressed less explicitly. However, I interpret the thousands of photos that have been posted throughout the years in the Chanel forum that gush about how gorgeous the lambskin is, or the color, or the hardware, as endorsing Chanel´s high quality. Every brand has flaws. I don´t think flaws are super common with Chanel, but they exist. It depends on how sensitive one is to variations, also. Good customer service is key in this regard, as is checking over your intended purchase before taking it home.
Understandably, people may have higher expectations at the Chanel price point than at a slightly lower price point. I have not had any issues with quality. I also find SAs to be wonderful, overwhelmingly. I actually have only had bad experiences with LV SAs! So you see, everyone´s experiences are different.
I have heard that vintage quality is superior. I do not know if this is true but maybe check out some vintage Chanel?