An very reliable, very unethical test would be to deploy LLMs on the internet as humans and gauge how other humans react (ignore, call out as LLM, engage, etc).

An very reliable, very unethical test would be to deploy LLMs on the internet as humans and gauge how other humans react (ignore, call out as LLM, engage, etc). There isn't much in the way of stopping a company from doing that (there should be!).