[david-cako]

Sort of, but it's unfair when you're buying booster packs online from folks that might be selling you pre-weighed packs from booster boxes. For this reason, you're really best off only buying booster boxes or individual cards online unless you really trust the seller.

[city41]

It used to be you could see what cards were in a Magic the Gathering booster without opening it by pushing each card one at a time to the edge of the pack and shining a bright light behind it. The edge of the packaging was white, so the name of the card would shine through.

I think most people into collectible card games know boosters aren't to be trusted in general.

[tasogare]

In addition to weighting, there was also a know vulnerability in the pseudo-rng method used in printing that allowed to know which boisters of a box were the most likely to contains the good cards (speaking of MTG).