Yeah theon,
The Faroudja chipa is the one that can "supposedly" clean up the garbage frames. Arsh has seen some clips of Mughal-e-azam and Humraaz . He would be in a better position to tell you more abt using Faroudja and using a cleaned up dvd.
My take would be that a cleaned up DVD is better than real-time garbage frame elimination. That's cos, the good-frame sequence (will be explained in the DIY tutorial) is best determined offline rather than in real time. In most EROS dvds, this sequence is constant. Hence technically there wont be any change between using a Faroudja chip and cleaning it a-priori. 
However, with older dvds like EVP pseudo progressive stuff, this wont work.
As for interlaced dvds.. You cant do anything with them 
 
There is, however, one advantage of using a reauthored dvd. In order to visualize the effects of using a Faroudja chip you need a HD display aka a HD digital TV !.. You dont need such a thing with a offline-reauthored dvd !
JB ..you are welcome 
