We've all seen them -- the Silly Listing Errors (SLEs) that make us giggle, wince, or rush to e-mail friends with the item number, ANYTHING but bid on the item!   Here are some common mistakes (and giggle/wincer material) to avoid. 

Common photo mistakes to avoid:

1. Listings with an out-of-focus photo
2. Listings  with a photo that's too dark
3. Listings where the item photographed blends with the background better than woodlands camo and your nearest tree 
4. Listings with so many props piled on and around the item the item is obscured.  Leave off the fake flowers and autumn foliage   
5. Listings where the seller DOESN'T SHOW THE ITEM LISTED! Why list an item as a sewing machine if you won't bother to move the VCR tapes off the foot pedal, let alone move the TV off the cabinet you're theoretically trying to sell?  (EBay won't let me list the auction number here, sorry)  
6. Listings with a photo with a reflection that reveal MUCH MORE INFORMATION THAN WE WANTED TO KNOW about the photographer  

Common descriptive mistakes to avoid:

1. Listings with cutesy typography , L**KY, L**KY, L**KY (eBay thinks I am creating an unauthorized link if I use the usual symbol for at)
2. Listings with the name or brand of the item being sold mangled (doesn't that make it harder for searchers to find it?)  No one who does a search for an item by a specific designer will find it if you can't spell the designer's name!   This is true for collectables, too.  Unless you want to give it away, spil it rite!  If it's spelled incorrectly, some folks won't bid because they are concerned the YZZX item may be a knock-off and the misspelling was deliberate so the speller/seller can truthfully claim they never said it was made by that well-known designer YZXX. 
3. Listings with misspellings that verge on perspired creativity or the bazzar
4. Any mass-produced item described as RARE.   If it really is RARE, those bidding will know and bid accordingly.. unless it's listed the week the high-dollar collectors are all off at an international collectors' convention on another continent.  A wise potential buyer will research the XYZ collectable item BEFORE bidding, but you need multiple bidders for success as a seller..  When I see RARE in a listing, I wonder what else the seller is exaggerating and I don't bid.   
5. Any listing with SHABBY CHICK. (I'll stop there). 
6. Any listing describing the wonderful detailing/decals/finish/woodgrain/hand-rubbed finish of the item in the picture, which is COVERED by accessories/a footpedal/decorations/packing materials that both obscure and can easily damage the item.       
7. Listings with descriptions in black print on a dark blue background,  florescent blue on a red background that makes the type visually vibrate, and worst of all, blocks of type designed to flash while you're trying to read!  
8. Telling a potential bidder who asks politely for a legible description that  I'm the seller and I can read it 
9. Scolding every potential bidder for two paragraphs because of the inconsiderate you-know-what non-payer who ruined a great auction and wasted waaay too much of your time a hundred feedbacks ago.  Just list their names.  Then we'll know to avoid them, too, and you can skip the ranting aimed at the rest of us who DO pay.      

Common procedural mistakes to avoid:

1. Starting bids by the seller that are higher than the average winning bid for a similar item.
2. Failure to research the previous sales for a similar item before deciding on a starting bid.
3. Starting bids that are completely out of touch with reality (i.e. US $39,700.00 more than the most expensive similar item I've ever seen listed on E-Bay in one case, with absolutely zero explanation and next to no description.  And no, it wasn't a listing mistake.)  What's with that? 
4.  Listing a new photo angle of the same item when relisting, while eliminating the original photos.  Sure doesn't give me a warmy fuzzy...

Anyway, that's my own two cents from the buyers' side.  Thanks to all the good sellers who make buying things on e-Bay a pleasure.  I hope my semi-tongue-in-cheek observations will be just as semi-useful  when it comes to avoiding sillylistingerrors. 

And the usual disclaimer, all opinions expressed here are my own.  Suggestions on what to do with non-baying pidders may or may not align with eBay policy -- since I'm not a seller, I don't know.  Happy bidding to all!