Trading and Gifting to make nice

[SkiRich]

I developed a large and wide civ with over 15 cities spread on three continents, so I have plenty of luxuries. I also have plenty of commercial, so I dont need gold. I'm playing with 10 other AI civs.
When they come and offer lux for one of my lux I make the trade, when they come with gold for my lux, I gift it away.

Seem though that some of these civs, especially the ones I gift things to, dont seem to improve relations with me. I know some of the agenda items dont line up, so thats that, but I expected more of an impact for the gifting.

Can I buy my way to better relations?

[Exemplar]

There is a diplomatic bonus for a favorable trade. It doesn't need to be a free thing, but it needs to be a relevantly helpful thing, like perhaps iron for 2g/turn if they have none and want it. You can't keep giving them more to improve that, though, it's just a 1-level sort of thing, and expires when the trade that granted it expires.

[SkiRich]

Originally posted by Exemplar:

There is a diplomatic bonus for a favorable trade. It doesn't need to be a free thing, but it needs to be a relevantly helpful thing, like perhaps iron for 2g/turn if they have none and want it. You can't keep giving them more to improve that, though, it's just a 1-level sort of thing, and expires when the trade that granted it expires.

How can I tell it’s in effect?

[Exemplar]

Listed in the tab on diplomacy screen with the plus and minus modifiers