You can definitely taste the difference when you kiss your wife after she has been sucking cock. Her lips, mouth, and tongue taste much different, even if the guy does not cum in her mouth.
I love kissing my wife after she has been sucking cock, especially right in front of the guy she sucked or is sucking. I love it when she stops sucking a guy's dick and kisses me, then goes back to sucking his dick. I also love it after she lets a guy blow his load in her mouth. I can taste the cum on her lips and teeth and tongue. Very hot!