How does eBay seller guarantee hot packs?

[G1911]

Presumably resealed in this case, but you can do this by weighing the packs and picking out the ones that weigh more. A relic weighs more than a decoy thick card (for most sets, at least). A plate weighs more than a base card. A legit hot pack won't be any more likely to produce a superfractor or autograph, but careful weighing can pick out 'good packs'. Some scummy people bring scales to the card aisle for this reason, I've seen them do it at Target.

Alternatively, one can sometimes pick the good pack by simply opening a box because the hit is always in the same spot. A surprising number of sets are like this, where if you opened the hobby box you know which pack it's going to be that has the hit.