Good Character

Q: When complimenting someone, do we have to actually mean what we’re saying to them? 

For example: If I tell someone I like their clothes to be nice, do we have to actually like their clothing to be able to compliment them? 

What if we don’t think anything of it or don’t actually like it or dislike it, for example, would this be lying or deceit?

What about when it comes to marital relationships? Compliments would be good for the relationship I think but do you have to mean them every time you compliment your spouse? Or would it be okay to just say it to make them happy even if you don’t actually think that lying to one’s spouse is permissible. I think I’m pretty sure but is that only when they ask you, for example: "how do I look?" and you respond with a lie to not hurt their feelings. 

Can it also be without them asking too, like you spontaneously tell them for example “you look nice today” when you might not actually think so?

Q: If it is permissible to delay denouncing evil (النهي عن المنكر) for a good reason, then if I see someone cursing, for example, if I advise him and he curses and he does not respond, and I say I will delay the advice until he calms down, but he calms down and I did not advise him, and two days passed, should I advise him after two days or is the obligation waived? And why is it waived when it is a debt?