One thing you can do is put a little of something you like to drink e.g. chocolate milk or something. Put the semen in a wide mouth glass. Mix it and then bottoms up. Also as a deodorizer have eat something sweet such as strawberries about an hour before.
Also get him to take Milk thistle this will clean out his system one to two capsules a day for a month. Then cut back to Once in the beginning of the month and once in the middle of the month. Hope this will help you. :)
I bet that the foulness is, in fact, due to the cigars and not an STD. Anyway, As for the taste and smell of the semen, I recommend that you have him drink those super sweet fruit juices, like grape or pineapple juice, on a regular (daily) basis. And, have him cut back or better yet, ditch the stinky cigars... I don't know how you can stand it!