Pattaya isn't like the small islands where low season might mean things shut down.
Everything is business as usual all year round. The girls don't leave for low season, you will find they will actually be hungrier for money and those girls that are always busy or you don't get a reply from on Thai Friendly suddenly start messaging you back. It's a good time to go.
I live in Jomtien and the wet season is unpredictable. You could come and see no rain at all or you could get rain everyday. Usually it lasts 30 -90 mins or so but some days it does rain all day but that is not often. Occasionally the roads do flood but odd bad day of weather should not be a determining factor.
The price of hotels in low season is just laughable too, many £25 a night or less for decent hotels.
I don't think there is ever a bad time for a guy to go to Pattaya. The worst time and when people moan the most is hot season March - mid May where it is brutal. That is lot less fun to be out and about town than waiting an hour for downpour to stop