Sure I can clear it up.
What happens is once they are into a potential deal, they go into exclusivity with the buyer, and we get brought in for a wack of interviews and going through their docs. Part of that period includes NDAs all around, and the agreement that they give us access to whatever we need (with sometimes some back and forth over IP). So could they lie? Technically yes, but as we ask to see things to demonstrate that what they said is true, and it would break the contract they've signed with the potential acquirer, that would be extremely risky. I have heard of cases where people did, it was discovered after the deal, and it retroactively cost the seller a giant chunk of cash (at risk of even more giant law suit). We typically have two days of interviews with them and we specifically talk about tech debt.
Our job is to ask the right questions and ask to see the right things to get the goods. We get to look at code, Jira, roadmap docs, internal dev docs, test runner reports, monitoring and load testing dashboards, and so on. For example, if someone said something vague about responsivness, we'll look into it, ask to see the actual load metrics, ask how they test it and profile, and so on.
I got into because I had been the CTO of a startup that went through an acquisition, knew someone in the field, didn't mind the variable workload of being a consultant, and have the (unusual) skill set: technical chops, leadership experience, interviewing and presenting skills, project management, and the ability to write high quality reports. Having now been in the position of hiring for this role, I can say that finding real devs who have all those traits is not easy!