Hell, you could even add option to spit or swallow for some extra nutrition and reward for really high paying customers for the cost of slight mood penalty. There really should be an option to use condom or not to reward higher paying customers. It doesn't spend the condom, but no cum splatters and the condom animation triggers.
Currently the time flows so fast that it is hard to comprehend.
Could you add a counter to the shops that informs how many units you have of the product you are about to buy.
