I noticed on ANS7 release when a similar discussion started, that for me... it was impossible to make out card borders in the packs that are foil. But for the "white plastic" packs, in good light, you could make out different border colors. Still very tough. I bought a case of ANS7 but didn't get a sketch card or gold border in my packs. I did purchased one of each for my set so played around with putting the sketch card in a wrapper with other cards. Under best possible circumstances, I could kinda, maybe tell. Don't know how someone could reliably do this in a store without being well practiced.
In the "Are these guys NUTS" thread, I posted some experimentation I did with ANS8 that would work great if you bought cases and were trying to find "hot packs" at home. I'll include the post below since its more appropriate here. I found when openening the packs within a box, there was a definite pattern and once one ascertained where you were in the pattern by openening the first two packs, you could tell where silver borders, tags, magnets, etc. would be. I only found one gold and one sketch in the case I purchased so can't tell how to detect them by position. But here is some other interesting info...
I didn't weigh packs as I was opening them so did a little experiment. I have a digital postage meter (on the cheap end). Previously, I posted the repeating pattern of 6 packs that I found when opening my boxes. So I weighed the various pack combinations using just the cards, as I have opened all my packs. For each combination shown below, I weighed multiple times using different cards but results where consistant. So here were the results on a cheap postage meter in grams:
16 grams = 6 base cards - Pink border - Pack to the Future combination
17 grams = 6 base cards - Pink border - Magnet combination
16 grams = 6 base cards - Pink border - Movie combination
15 grams = 6 base cards - Sliver border - Pack to the Future combination
17 grams = 6 base cards - Pink border - Lenticular Tag combination
15 grams = 6 base cards - Pink border - Movie combination
So the real item of interest is that in the pack I opened with the sketch card... the sketch card was an additional card in one of the 6 base cards - Sliver border - Pack to the Future combination. This combination weighs 18 grams.
Unless you were to run into some odd combination that wasn't planned , with something like two magnets in one pack,or 3 extra base cards (which I didn't when opening 8 boxes of packs),
clearly the heaviest packs should contain a sketch card. I can see how this helps if you are at home opening packs but is someone really going to take a scale into Walmart or Target? If so, they are more desperate than I.
My gold border card I opened came in one of the 6 base cards - Pink border - Movie packs and replaced the pink border card. Weight was no different than the normal pack.
Conclusions:
* Sketch cards can be determined by pack weight
* Silver border, tags and magnets can be predicted by the pack content pattern if you know
where you are at in the pattern (by openening the first two packs in a box stack).
* I have no idea how gold border cards can be predicted. I know where the one I found was in the pattern order. Perhaps a certain box in each case contains one? Don't know. I only have the 1 case/8 box data set to go by. If any benefactor would like to contribute more cases to my research, please feel free to contact me.