Oh yes, the Pioneer SX-1980 has two phono inputs, and I have two turntables connected to it - the Denon DP-59L with Dynavector 20x, and a Pioneer PL-570 with a Clearaudio Maestro Wood. But the Denon is the better TT, and so I almost never use the PL-570.
Actually your idea of having a "less good" cartridge on the PL-570 to play crappy records on isn't a bad idea at all...
Clearaudio Maestro Wood is far too good for such purpose of "scouting".
More than 2 decades ago I figured out that total lack of King Crimson LPs was a situation that had to be rectified ASAP - particularly Starless and Bible Black album. Pre internet days, still Yugoslavia, second hand shop(s) was the only reasonably available option. And I got it - except that the ex-owner was a smoker. Beautifully preserved pressing, jacket, etc - and in the middle of the track I like the most, there was a cigarettte ash mark ... Yet, given the fact that this album is/was kind of rare, specially at THE TIME AND PLACE, I haggled till the price was very reasonable - even without the track I was really after.
With brand new Benz Micro Ruby on my main arm, there was absolutely no taking chances with cigarette scorched track. Yet - I was dying to hear it again after more a decade my original copy dissapeared. Then I stumbled upon an olden stock of Ortofon Stylus 20 styli - at a crazy low price.
I had one OM body lying around - and mounted this combo to my beloved Transcriptors Vestigal.. WOW - OM20 in Vestigal is a treat in anyone's language, it measures and listens
superbly .
OK - at the dirt cheap price for the OM20 stylus I decided to hear the ash scorched track. I was at the highest alert to lift it from the record at the first sign of anything that sounds significantly out of ordinary. Barely more disturbance than from a bad or stamper used for "a couple copies too much " - phew... But the term "scout listening/cartridge" was born.. Later, Ruby negotiated that scorched track with the same ease, of course producing even better sound.
http://www.youtube.com/watch?v=R50e3ZP1TfY&list=PLAE88C109FAEEC393
I should have bought entire stock of Stylus 20s back then - now I am on my last one from that batch. At present price for the Stylus 20, I "guess" scounting will have to be done with something cheaper once this last one gives up the ghost...