No one said 3-cyl engines in general are bad or that people who own 4-cyl cars think they own super cars or whatever. What I said is that the 3-cyl engine on the Polo SOUNDS less refined compared to the 4-cyl engines on the other cars belonging to the same class as the Polo.
My car at 100-120 km/h is noisier than my friends' Swift, i20 and Punto at the same speed. When I say this, I do not mean that the 1.3 MJD is not at all noisy. All I'm saying is that those engines sound more refined. I hope you understand what I'm trying to say. Try cruising in a Polo at 120 km/h and then do the same in a Swift or Punto. The 1.3 MJD sounds less stressed than the 1.2 TDi. (The reason I'm saying this is because my girl bought a Polo and a Punto on the exact same day so I know how both sound as I've driven both extensively.)
And regarding the Vento. I recently had the chance to keep a Vento for a week. The Vento, on the outside, sounds all clattery. But on the inside, it is quieter than the Polo. Again like I said, it's the VW engines that are slightly more noisy, irrespective of 3- or 4-cyl, petrol or diesel. I read in many ownership threads that the petrol 1.2l Polo sounds like a diesel at times.
VW should have provided better sound deadening at the price that they are charging.