For those who're interested.
So I've toyed with what y'all call "loving whispers" and I call "night whispers" off-and-on for several years. Overseas duty has sometimes interrupted this; as have other real-life dramas (like preparing for overseas duty, returning from overseas duty, etc). But I've used the technique for quite a while, and am fairly convinced that - specifically in our case - it works.
I'm a scientist/engineer by training, so validating practices interests me. For my LWs related to cuckolding, I developed about 8 main scripts that I used off-and-on over the years. That way I reinforce the same words and common themes. But I also interspersed among them other scripts dealing with self-esteem, fitness, discipline, etc. But for cuckolding, it was the same 8 scripts, saying the same basic things in different ways.
To see if the scripts were "moving" her at all, I identified several themes common to the cuckolding scripts: Would I have unrestricted access to her mouth? Her Pussy? Would I get to know about her dates? Select who she dates? Watch them have sex? Would I be expected to clean her pussy with my tongue? Would she go "black cock only" for periods of time? And, as something of a "control question," Would I have access to her ass (this as a control because she's hard-over adamant that anal sex won't happen; so that variable shouldn't change).
I wrote a really simple "survey monkey" app for her phone that used a variety of 60 questions (not all the questions every time) to elicit changes in the themes noted above. And I slipped into her NWs a suggestion that she would enjoy giving me glimpses of her opinions on cuckolding now and again. the app would ping her a couple of times a day for input. And it would aggregate the input to the 8 themes being tested. So that, essentially, I have data for every day (sometimes twice or even three times in one day) illustrating what, if any, changes there have been with respect to her perspectives.
These "spider charts" are a simple way to illustrate the data. There are four charts: One representing a "baseline," taken after just about a week of night whispers. Then "Round One" represents data taken on a single day (averaged where necessary) about a month later. Rounds Two and Three were each also taken about a month after the previous snapshot. I used the data from other intervening days to look for sudden points of discontinuity; and there were a few. She almost had a D/s relationship with a black guy she met at the gym, for example. During that period of time her perspectives on "BCO" and self confidence moved quite dramatically. After the "romance" petered-out, her perspectives returned to almost where they were before the event (but not quite; the experience did shift her perceptions more than just the night whispers alone were doing).
Any way; the graphic below shows that, in this completely unscientific, unreplicable study, my wife's perceptions WERE modified quite significantly by night whispers. I should note that she was a knowing participant (she knew that I used NWs, but didn't know when, or the specifics, unless/until I shared scripts with her); she was already a "hot wife," and was willing to consider the things I was encouraging her to do (with the exception of anal); and she's naturally submissive (and suggestible).
Separately, a year or so later, I did a similar experiment over several months where I used night whispers to try and change the color of nail polish she used. I thought this would be an easy way to see if the technique worked. If I could get her to use a certain nail polish using NWs, I'd have strong support for the technique. I'm sad to say, that experiment didn't work as well. I did get some changes in color and behavior (I suggested she re-color just her fingers or just her toes), but it didn't correlate particularly well with the whispers I'd been giving her. When, after the experiment ended, I shared the results with her, she responded "Silly boy: I'm not going to change something as important to who I am as nail polish on a whispered whim!"
~grin~ So that shows how women equate sex vs nail polish!