I personally would not care one whit if my wife found out I was trying to gather intel. Eventually, she did, in fact, find the voice-activated recorder in her car, the GPS-enabled cellphone in the trunk, and figured out that I had a keylogger on our home computer. By then, I had more than what I needed to "hang" her.
In every case, I said the same thing: "Everything I'm doing, you may not agree with, but I'm doing to try to save our marriage and keep our family together."
I still think the best way is to simply catch them leaving their cellphone lying around, and read their text messages. I haven't seen an affair yet that didn't use TMs as its basic communication currency.
