Signature campaign is one of the sign that the project really have a serious plan behind because they want to pay the bounty manager to manage the bounty. The better the manager means the project really want to pay more to promote their project and i think it's one of the sign that the project team want the project reach a successful in the future.
i am thinking there is no correlation with project seriousness and signature campaign . Most bounty campaign have allocation for signature and it didn't represent about project quality. except if this campaign using major coins as reward, such as bitcon or usdt that be common currency to pay bounty hunter.
Most crypto investors are here so the signature campaign has a huge impact on the development of an ICO. It's been the best way to advertise a certain token. Promotions like this is necessary for the growth of an ICO so most investors would be able to see its potential.
it is be one of marketing campaign to promote project in this forum , alot investors in this forum and some of them also be bounty hunter. so using signature campaign was good strategy to get internal member as target promotion.