Well, Zubat are numerous, but they don't disturb be that much. I think they're as much annoying as Pidgey, Rattata, Zigzagoon and every other Pokémon you find at the beginning of the game. So, not a lot, we have to do with it anyway, and when we start our journey we often need at least one of them.
BUT. Tentacool. Who need a Tentacool for their team? I guess not a lot of people. So why are they so numerous? They ruin all the pleasure of surfing when it's to early in the game to have repels... I can't stand them. And they're ugly. And poison your team.