Summary: In the barter screen for marriage I found that I was able to hit the automatic offer button without enough money to pay the Clan leader. I clicked done and the barter failed but I received Charm experience, enabling me to level my charm infinitely.
How to Reproduce: Started a new game in 1.6.4, played for a while and decided to get married early but wanted to marry Unqid's daughter Anidha. After passing the Charm checks with her I hunted down Unqid after smithing and selling the weapons and getting 12k dinars. I met Unqid outside of a city since I was Clan rank 0. I talked to him about settling the final marriage stuff, offered all my money and hit done and without having anywhere near enough and he rejected the offer but I got some Charm experience. I then left and talked to him again and this time just hit auto offer and done. The auto offer didn't put anything up but hitting done still gave me experience. I found I could repeat this everytime I left conversation and returned.
How to Reproduce: Started a new game in 1.6.4, played for a while and decided to get married early but wanted to marry Unqid's daughter Anidha. After passing the Charm checks with her I hunted down Unqid after smithing and selling the weapons and getting 12k dinars. I met Unqid outside of a city since I was Clan rank 0. I talked to him about settling the final marriage stuff, offered all my money and hit done and without having anywhere near enough and he rejected the offer but I got some Charm experience. I then left and talked to him again and this time just hit auto offer and done. The auto offer didn't put anything up but hitting done still gave me experience. I found I could repeat this everytime I left conversation and returned.