That kinda depends on the type of game and type of gameplay. Speedruns are very obviusly something you can watch and not spoil yourself. There are also games that have hard learning curve and watching someone skilled is fun and a way to learn the game ( europa universalis for example ) . Some pepole want to watch someone role playing beacuse they know they will never be able to do that in a milion years ( i for example beat mass effect 3 times always taking the same decisions beacuse i just couldnt force myself to do somdthing diffrent ) so you might wanna watch someone who will do actual evil playtrough.
That kinda depends on the type of game and type of gameplay. Speedruns are very obviusly something you can watch and not spoil yourself. There are also games that have hard learning curve and watching someone skilled is fun and a way to learn the game ( europa universalis for example ) . Some pepole want to watch someone role playing beacuse they know they will never be able to do that in a milion years ( i for example beat mass effect 3 times always taking the same decisions beacuse i just couldnt force myself to do somdthing diffrent ) so you might wanna watch someone who will do actual evil playtrough.