I'm only suspicious if they don't simultaneously and eagerly show me their Github so that I can see what they've accomplished.
Sometimes this industry is a lot like the "finance" industry: People struggling for credibility talk about it constantly, everywhere. They flex and bloviate and look for surrogates for accomplishments wherever they can be found. Peacocking on github, writing yet another tutorial on what tokens are and how embeddings work, etc.
That obviously doesn't mean in all cases, and there are loads of stellar talents that have a strong online presence. But by itself it is close to meaningless, and my experience is that it is usually a negative indicator.
Actually it is incredibly difficult, because you no longer have access to your previous employers' code bases and even if you do, it is illegal for you to show it to anyone.
So the person never does anything outside of his employer's IP? That's unfortunate, but as a heuristic, I'd like to see stuff that the person has done if they claim to be in a field.
Perhaps other people don't care, and will be convinced by expertise without evidence, but I'm busy, and my life is hard enough already: show me your code or gtfo. :-)
And frankly, when you hire a manager or executive, there's not generally a single artifact that you could use to examine their value-add. You can see perhaps the trajectory of a company or a division or the size of their team over time, but you can't see the pile of ongoing decisions and conversations that produce actual value.
I think the flip side regarding code is, the stuff I do for fun outside of my employer's IP is not at all representative of what I do at work, or how. I pick topics that interest me, work in languages that my company doesn't use, etc, and because my purpose is learning and exploration, often it doesn't end up as a finished, working, valuable piece of tech. I deliberately don't do anything too close to my actual work both b/c that just feels like working longer and because I'm concerned it would make ownership of the code a bit fuzzy, and perhaps it would be inappropriate to consider open sourcing. Because my side projects are eclectic and didactic, I rarely put it in a public repo -- but it has served its purpose of teaching me something. If I shared all of my code side projects, they would show an unfocused person dabbling in a range of areas and not shipping anything useful, because that's what's fun ... whereas at work, I am focused in a few quite narrow areas, and working on customer-facing features, because the point is to build what the company needs rather than what I enjoy building.
That's only true if you don't know how to read code. I simply read their code and based on my level of expertise, I can determine if someone is at least at my level or if they are incompetent.