From a logical perspective, if the question whether a transition system simulates or bisimulates another one, you may answer that in any way that is "adequate". This means, a simply "yes" or "no" is not sufficient, you have to give any valid reason why it is so.
For instance, if the structure simulates another one, and you can guess a simulation relation and prove that it is one, it is fine. If you can prove that there does not exist one, it is also fine, but you have to make sure that your proof is a valid one.
From a more strategic perspective, I would not recommend this, since computing the relations if often feasible when you have some experience. And even if you have a mistake in there, you may still get some points, while for an invalid proof, it is not clear whether to give points.