I bought SVC chaos and SamSho4 from him (selling under his moms account of course), and they were both legit, as stated in the auction. I won the bids on Monday, got the games Friday.
If the description says "THIS IS NOT A BOOTLEG", then its probably not. If the description mentions nothing about authenticity, and its a Euro Kizuya Encounter with a 49 dollar buy it now, its probably not gonna work out.
Bottom line:
These people sell boots. These people sell real carts. Sometimes its hard to weed through it all, but it can work to your advantage.
I bought a legit samsho4 cart for 35 bucks, took it apart, sprayed it with electronics cleaner (was really dusty), and popped it in my 6-slot. The end.