Shifts in collector preferences, changes in the popularity of certain sets, or the release of new cards can all impact the desirability of older ones
Once per turn, during the Battle Phase, you can (Quick Effect): Immediately after this effect resolves, Synchro Summon using this card you control
You can tell how effective the moves will be by looking at the moves themselves in the bottom right
And then theres the question of expertise
Established dealers can often tell you the card's history -- where it was graded, when, and sometimes who owned it before
pfm October 2, 2023, 3:08pm 7 @Dyl is saying that the double holo is a misnomer because the amount of holo material in the card is the same, there is no additional holo layer