Yes. That is just a theory. But I find softer packs works for CG and DF. I once got flygon ex from LM in a soft pack too. But we could be totally wrong.
My theory, it's luck. As far as I know, there is no definitive test for an Ex.
As for luck...
In November 2005, at a City Champs, I got 10 boosters and got 1 Jolteon Ex.
Feburary 2006, another Cities, got 4 boosters, got 1 Jolteon Ex and a Kyorge *.
My next Ex came late August, 2006, after buying at least 1 booster every week inbetween.
Well when I said hard/soft packs I was refering to the bend test. So if a booster bends quite easily I would say that was a soft pack. Though as I said last time this is not proven.
Well, I Got 5 of those packages where you get three booster packs, a coin, and a promo card. For each one of those, I got an ex (aggron ex(cg), Politoed ex (uf), Ho-oh ex (uf) Deoxsys deffence (dx), Vaporeon ex (ds))
Good luck?
well i tryed bending my frens RayRay ex δ it was soft and i tryed bending his vappy ex and it was hard.....Conclusion ...DF soft packs....CG down Hard packs
anyways, CG packs are the soft ones, at least my friend tried it and got a Swampert ex... i haven't done the bend test yet, i haven't had a chance to buy a pack...
I have bouth boxes and only 3 exs
But if I bouth the booster alones i get more luck
Example: I bouth 3 Booster and I get 1Metagross star and a mew- ex
my friend get a Fligon ex in 3 Boosters
so bought few booster
The first two packs i bought i got : GengarEX and a holo fearow, but i'm not sure if thats really considerd lucky. (i started collecting when firered and leafgreen came out.)