My comment (that I was going to do here) turned into a post...
https://ecency.com/hive-150329/@forykw/brainstorming-alternative-pool-for-delegations
If people would like to read it and let me know more, I would appreciate it.
I am not sure if would stop this kind of vote-selling, but I would be willing to explore the idea and make some efforts towards possibly testing it.