Gary O 1 wrote:
Another show that used the disguise plot device a good bit was WILD, WILD WEST by Jim West's friend, Artemus Gordon.   
The Secret Service must have had a lot of masters of disguise on the payroll in the Grant administration. There was a time when Ross Martin was out of the series for awhile--he had a heart attack or something--and he was replaced by rotating guest stars like Charles Aidman and William Schallert. Masters of disguise, all.