All I can think is that Dennis James didn't like the form factor of the ECM-51. At first they gave him an E-V 654A which sounded like a**, then he had an RE-50, then an SM-61.
ISTR Barker had an ECM-51 in a very early show, then in the next segment he had an RE-55, then back to the ECM-51.
Bert Convy on Tattletales and Monty Hall on ANBTC each went through a succession of microphones. It was probably a decision made by CBS engineering and the audio technician.
One problem is that studio 33 has more reverberant acoustics than it should have, and it has parallel walls. I don't understand why they kept giving these guys omnidirectional mics. At one point Bert Convy had a Shure SM-59 cardioid for Tattletales.
Password Plus started out with Shure SM53's but Bobby Sherman thought short shotgun mics would kill some of the projector fan noise from the Kodak Carousel projectors used in the desk and for the puzzle board. Little did he realize that the short shotguns he wanted were condenser mics with a lower diaphragm mass than the dynamics they replaced, so they were a bit more sensitive to the fan noise, but he was dug in so they kept them.
On Super Password the wireless mics picked up a lot of static from the neon in the set.