That is precisely the
problem if we can call it that. How much due-diligence can be applied before selecting a product or service to advertise or promote? Some do end up scamming and some do not. I suppose if signature campaign participants investigated and concluded there were no major concerns that they were dealing with scammers that would be the best they could do.
You have a signature advertising a mixer that uses exchanges to "clean" coins...which is even more centralized than a protocol-based mixer.
If we stop advertising products that might turn out to be scams in the future, then there is nothing left to advertise. Everything is potentially a scam. Plus, someone might prefer the comfort and pricing of a mixer over decentralized solutions.
You my friend is the cheapest person I have ever come accross on the internet. You can sell your conscience and your soul for a pot of porridge