The list below are signs that a seller is probably selling fake L.A.M.B. items:

1. The seller has multiples of the same item for sale, all new with tags (NWT), even though the item is long sold-out.  These will generally also be items that sold out at retail prices for way under retail.
2. The deal seems too good to be true.  For instance, you are not going to get a real WDLMG Hoodie for $99.  Ever.
3. The item will take an extended period time to ship. (item will ship in 2-4 weeks, etc.)  Please be aware that if you do not receive your item or you find that you have received a fake, Paypal will only accept a claim within 45 days of payment. If you file a claim with Paypal after the 45 days (which is when some sellers say they will ship), Paypal will not protect you.
4. The seller is based in Hong Kong.
5. The inner care label should read "Where did my lamb go?" On some fake tops the tag reads "where NIN my lamb go?" instead of "where DID my lamb go?"  The text on the flag that the lamb is holding is also unreadable on some fakes.
6. The inner silk tag is not silk, it has either no shine to it or looks way too shiny, and/or the word 'LAMB' on it is printed backwards. Real silk tags should have just a bit of sheen to them.
7. The seller is unwilling to take additional photos and/or is rude in answering your questions regarding the item’s authenticity.
8. The auction repeatedly claims that the item is “100% Authentic.”  Sellers with real items don’t generally feel the need to try so hard to convince their buyers that their items are real.
9. The seller is selling mega white bags with white LeSportsac logos along the top of the bag. Real mega white bags have very dark grey logos that blend into the black piping at the top of the bag, and you can only see the logos if you look very closely.
10. Multiple sellers are selling the same bags with the exact same pattern placement, all NWT years after the bags sold out.  The sellers will also often be running one-day or 3-day auctions.  Watch out for this with the first season L.A.M.B. print girlfriend bags, second season hella hobos, and the mega white baby barrel, large backstage, concert, and girlfriend bags -- check the rest of ebay before bidding.  If you see lots of the same bag with the same pattern placement, the bags are all fake.
11. For Where Did My Lamb Go? (WDMLG) hoodies, the words on the real hoodies do NOT line up across the zipper on the front.  On the fake hoodies, the words DO line up across the zipper.  (Seems backwards, I know.)  It is therefore very easy to tell if the WDMLG hoodies on ebay are real or not - check the word alignment on either side of the zipper.  Also, some fake WDMLG hoodies have an upside-down "y" in the word "my."  UPDATE:  Proceed with caution even if the words don't line up across the zipper - a new batch of fake WDMLG hoodies with words that not not line up across the zipper are supposedly coming soon. :(  Also, be aware that 99.9% of the WDMLG hoodies on eBay are fake.  It is VERY rare that a real one pops up, and when it does, it won't be cheap or NWT.
12. The seller does not accept Paypal - they will only accept payments through services like Bidpay and Western Union that do not offer the buyer the same level of protection that Paypal does (guess why!).
13. The LeSportsac tag on a NWT bag has a lot of space between each of the letters in the word "LeSportsac."  On the real tags, the letters are just about touching each other.
14. The seller is charging an outrageous amount of money for postage.
15. The seller has icon multi bags with yellow interiors - real icon multi bags have lime greenish interiors.
16. The seller is selling logo tanks with poor quality embroidery, or in color combinations that never existed during the season the tank is supposedly from. 
17. Don't be fooled - some sellers have now caught on that their tags are giving their bags away as fakes, so they are now listing their bags as something like "98% NEW, secondhand , without tags" -- but they are still selling a bunch of the same fake bags with the same photos coming from Hong Kong. 
18. If an unusual number of bags in the same print suddenly pop up on ebay at the same time, chances are that they are fake.


List of known fake L.A.M.B. items to appear on eBay:

Chain Lock Racerback tank
Snakeskin Hoodie
Wisteria Poem Tee
Victory Hoodie
Chain Lock Hoodie/pants
Wisteria Poem Hoodie
Rasta Stripe Hoodie
White L, A, M, B is for... pants
White L, A, M, B is for... hoodies
BLACK L, A, M, B is for... pants
BLACK L, A, M, B is for... hoodies
Flocked Leopard Hoodie
Collegiate Pants White
Collegiate Pants Taupe
Collegiate Pants Black
Collegiate Hoodie White
Collegiate Hoodie Taupe
Collegiate Hoodie Black
Logo Tanks
WDMLG Hoodie
Heart Crest Hoodie
Banner Hoodie
Fleece Gothic Hoodie
Peacock Feather Tank
Pirate Flag Tank
Pirate Ship Tank
Pirate Ship Tee
Cropped Turtleneck
Heart Crest Tank
Lace Logo Strappy Tank
Love Definition Tank
Collegiate Tank
Rugby Shirt
White WDMLG Tank
Made With Love Tee
What Color Is Love Tee
Holiday Logo Banner Hoodie and Pants
Mega WDMLG Scarf
Lace Logo Strappy Tank

First Season L.A.M.B. print Girlfriend bags
Second Season L.A.M.B. print large hella hobos
Mega White Large Backstage bags
Mega White Baby Barrels
Mega White Girlfriend Bags
Mega White Concert Bags
Icon Black Large Backstage Bags
Icon Black Baby Barrels
Icon Black Concert Bags
Mega Black Baby Barrels
Mega Black Large Backstage Bags
Icon Multi Large Backstage Bags
Icon Multi Streetwise Messenger bags
Rasta Ribbon clutches
And any bag listed NWT that doesn't come with a charm is suspect!