There is something to take into account; some guys (like me) follow a code of keeping our friend's girlfriends/wives off-limits in any regard (or at least, pretending like we do)
So, if you tell/ask them something hot about your own girlfriend; they won't reply with a pervy comment as if it was about any other girl. Most of them will just laugh and just say something like "lucky you", "she seems like a good girl" or something along the lines.
The key is to keep pushing until they are certain that if they say something pervy about our girlfriend/wife, we won't get upset and we will even like it. Once you reach this point, there is a higher possibility of them confessing what they do thinking about our girls. Not before.