hmmm... just make sure they're legit, that's all I can say. Since if you're able to RNG effectively then little does matter if people give you pokes with poor IVs since, after all, you're planning to breed them for better ones, and since you're starting with the whole DW stuff just focus on getting as much breeding material as you can, also think about it, it is already difficult for you to make trades in the first place, so 1:2 or 4:2 is the least thing you wanna do :P