It's something I try to ignore as best as I can.
Just have to accept that Oda finds it hysterically funny. Or maybe his editor pushes him into these nosebleed jokes, I don't know.
Like someone in the Spoiler section said, it feels like there are two different authors. One comes up with the original and funny gags, like the crab smile user who got outmaneuvered because he can only walk sideways, and then there is someone who insists to play the exact same pervert joke we've seen 50 times already.
It's only the one and only guy behind all jokes. Taken from SBS 92:
D: Back on Zou, when Momonosuke mentioned that he met Roger, I thought that for some reason or another, this was an adult that became a child and was using his position as a child to get spoiled by Nami-san and Robin-chan. Now that we know that Momonosuke is someone who leaped through time and whose actual age is still 8 years old, doesn't that mean he is just a normal Perverted Kid!? P.N. Taku Miso
O: Think about it. Remember what it was like when you were an 8 year old boy. That's right, you were a pervert. All young boys are perverted!!