The problem with swapping sites such as LoveHomeSwap or HomeExchange is that the owners of more desirable homes end up with more points than they can use. This is why single-purpose currency is nowhere as useful as multi-purpose currency, because with single-purpose currency, the best at any trade get too much of it and stop trading. In contrast, it's harder for people to conclude they have too much general-purpose currency --they can usually think of something else they want from other people.