This came from http://groups.google.com/group/mongodb-user/browse_thread/thread/d8940067b89cb839

$maxScan does not return expected results when it is >100

To reproduce:
> for(i=0; i<50000; i++){db.mxscan.save(

{'ts':i, 'nr':i%47}

);}
> count = 0; db.mxscan.find()._addSpecial( "$maxScan" , 101 ).forEach( function

{ count += 1; } ); print(count);
50000
> count = 0; db.mxscan.find()._addSpecial( "$maxScan" , 100 ).forEach( function { count += 1; }

); print(count);
100