At a high level any MSD program is set by the bank and the dealer cannot really manipulate it (outside of marking up the MF, but that’s nothing to do with MSD’s themselves).
But some dealers are familiar with MSD’s and some are not.
As always the key is to just do your homework, use the LH calculator and develop a target deal. Know exactly what the numbers should be, including MSD’s, before ever talking to the dealer.
And never rely on the dealer for guidance on MSD’s, many will say they’re “not worth it” just because they don’t understand them or don’t want to do them. Do the math yourself and you make that call, not the dealer.