These Matt Helm movies aren't that great but they aren't that bad either. They seem to most notable for inspiring Austin Powers which seems to have kept the 60's look, the photographer occupation, and even the femmbots.
Thats what I thought too when I watched the silencers. Also the final scenes remind alot of austin powers, the way the villians dressed and their secret cave layer all somewhat reminded of the first Austin Powers.
Well, Mike Meyers has openly credited these films, the Harry Palmer films (with Michael Caine), and the James Coburn "Derek Flint" films as the inspiration for Austin, along with other elements from the swingng 60's (the Avengers, Blow Up, Help!, etc...).
The films aren't that bad, although they get worse as they go along. The Silencers is the most fun. Still, they are better than most spy films of the era. The Flint films are better parodies of Bond, though.
The original inspiration of Austin Powers was the 1967 version of Casino Royale. Mike Myers got the idea when he heard "The Look of Love" on the radio and was inspired to create a character based on all of these old spy-fi films. The photographer cover was definitely taken from Matt Helm, the glasses from Harry Palmer, the crushed velvet suits from Jason King. The fembots most likely came from Dr. Goldfoot.