3D converters have zero specular effects meaning that the water or glass will never be seen as transparent and all textures will look like paper stains and all other specular effects will never be present.
Above all that the converters are guaranteed to give always a false depth.
Using Purlfrich glasses you will see many scenes with true stereoscopic effect due to camera's horizontal motion or object's rotation.
Another advantage of Pulfrich is automatic operation which detects motion parallax and presents stereoscopic effect immediately.
If no motion parallax exist the Pulfrich method will project 2D scene without false depth.