the thing that appalls me most about knockoff designer goods is not because there's so much out there, but because so many buyers inadvertently purchase them either because they are simply too ignorant or do not care about preserving the integrity of quality products and good design.

a scary result of this is that many good sellers who's accidentally purchased a fake or two will start selling these items.  these phony products spread throughout the land of ebay like vicious stds, mingling with the real deal.  and thanks to many of us with revolving closets, items can get passed around alot, resulting in garments, shoes and purses with dubious origins.  bottom line is, when fakes are mingled with authentic couture and well meaning sellers, it can be downright difficult to tell what's real.

so, i am writing this in hopes that more ebay buyers will take notice and avoid patronizing those cheats- those making huge profits on cheap goods that they lie & tout as the real deal... ripping you off.

some warning signs to look for:

1. terms like 'new arrival', 'just arrived', or 'new collection'-  99.9% of the time, sellers, despite their claims, do not have access to marc jacobs, cacharel and marni factories so they should not come across as factories.  occaisionally, a seller will mention the collection from which the piece originated, i.e., fall 2005.  this is not anything to be worried about, for they usually only have one piece from that particular collection (see #2.)
2. many of the same items in different sizes-  it is far cheaper for them to do that than list many different items in a few sizes.  note, it is helpful to check out their ended auctions.
3. if many sellers are selling many of the same thing-  much of this merchandise are purchased from the same factories.  however, i'm starting to see more and more of these evil sellers venturing out from their usual brands (see #4) to other labels such as cacharel, max mara, cop copine, jill stuart, robert rodriguez, phillip lim, mint, lanvin, theory, and tsumori chisato.  (i'm not buying mint on ebay anymore since it's becoming like marc... more fakes than real!)  they're also starting to peddle more fake moschino, burberry coats and coach bags.  i'm finding more and more fake marni too, much to my annoyance.  but luckily, there exists several good ebay guides on buying marni. 
4. too many of these labels in their inventory: bcbg, marc jacobs, diane von furstenberg/dvf, catharine malandrino, chloe, rebecca taylor.
5. lack of details that should be there-  couture clothing will have couture details such as extremely neat & precise stitching, novel material content, quality buttons, logos on hardware, subtle seams and other construction details, lots of interior tags with lots of information like: detailed material breakdown, care instructions, and size in several countries (exception: chloe & lanvin.)  sometimes there's a japanese translation or a hologram too.  all these should not look like they were printed in a third world country and on flimsy cheap tags.)

warning signs now obsolete:

1. sellers from china- granted, most chinese sellers are still full of fakes, but they've caught on and many are now registered in australia, usa, canada, new zealand, even uk (i.e., many places with chinese- you won't find them coming out of israel.).  there are a lot of fakes coming out of hong kong and thailand as well.  in all of ebay, there are only a handful of asian sellers that i trust (mushroom_city, hbean-closet, buttonjj and 08022257.)       
2. spotless feedback- a seller of fakes can receive 30 to 50 good feedbacks before a buyer will come along who is both in the know and bold enough to leave a neg.  once receiving negatives, these sellers simply open another account since it is easy to do so and besides, many buyers have no problems with sellers having very little feedback.  conversely, a less than stellar feedback doesn't necessarily equate to bad sellers because relatively new sellers receiving just one neg will see their feedback scores plummet.  so don't just look at the feedback numbers, read the comments.   

in closing, some more tips:

study the sellers' inventory including ended items.  study their buying history, whether they've had any transactions with sellers of phony goods.  study closeup photos carefully (of tags and hardware especially.)  familiarize yourself with the style, whether it comes in a particular color or size and what details should be there. 

very important!  familiarize yourself with the designers' tags.  an example:

these tags come from a fake new lanvin top from china.  now, we may scoff at the horribly fake tags, but it is disheartening when you realize this seller has over 2700 feedbacks and is 99.6% positive.

be wary if the seller cannot provide closeups of actual item.  be very careful of buying labels like marc jacobs on ebay.  do take a peek at their feedback, though don't rely too much on it.  power seller status only means the seller exceeds certain volumes in sales, has an account in 'good standing' (mostly if the seller doesn't owe ebay money or hasn't been blatanly caught violating a major ebay offense), and their feedback isn't totally dismal.  in short, it doesn't really mean anything.

i generally prefer to buy items that have not been purchased on ebay even though it is true the seller can lie about that, which is why you have to look at everything as a whole.  i also like to buy obscure labels and less profitable items such as brands like banana republic and damaged, used, or older goods.  when in doubt, ask questions or request more pix.   be wary if sellers are vague and/or withold information.  if your gut instinct tells you it's fake, most likely it is. 

let's not support these heinous people and hopefully, we can help cut down on the incredible amount of fake $h1t on ebay.  the imposters are only in business because people are buying!