unfortunally I see more and more fake cards on Ebay .... a lot sold from Asia, but also sold in the USA and UK.
Again FAKE Diamond and Pearl booster boxes from China show up at Ebay. The boxes have a Pokemon and number at front and for the back it looks as if it's a genuine Pokemon USA product. The boxes contain 30 cards; among these cards are non-shiny LV X cards.
Found it first last year when I bought a box with fake boosterpacks.
Since then I watch pictures a bit closer.
"gladly" for sellers a lot of buyers are just happy with the very good looking cards, also because of a lot of young kids have no idea (and also the parents do not)
It's very sad for kids that if they would like to play official tournements, they might get refused.
If you look at this site, you will find every genuine card-picture (add www.)
easy to find the right set to check with the set-symbol in front of the set
it is an site originated in the Netherlands
every picture is checked/uploaded by a Pokemon Professor/Gymleader.
Next to comparing pictures, the best to see if you have a fake card is to hold it in front of a lamp
with genuine cards you cannot see the back, with fakes you can see the back-side print through the front
In fake boosters (you will not notice the difference in the package) you will often find cards from different sets in 1 boosterpack.
Fake Ex cards will have a yellow border, where Ex cards from genuine sets have a shiny border.
Only exception sofar are the ex cards from the POP promo sets. They are released with yellow borders in the POP boosters and with shiny borders in the promopacks and promotins you can buy in stores.