In my own opinion, it is really needed for a bounty to have a strict rules so that other bounty hunters who spam and cheating on their works will not be tolerated to avail the rewards anymore. There are times that they are just copying the work/s of other, if you are the owner, it is very unfair for you to. If there is a change in rules, it must be posted on the bounty thread or bounty official channel/s so that the participants will catch up on it. Following the rules is very important for us bounty hunters to be successful in bounty hunting.