The only time I've found talking about a project to be a good predictor is when it's a type of project or tech stack that I'm familiar with. In that case, I can ask very specific probing questions about problems I'd encountered with that problem or tech. In answering these questions whether and how often they talk about specific solutions they came up with versus saying something along the lines of "well I dunno, I wasn't responsible for that piece" or "I'm not sure about the details, I was more involved with the higher level decision making" can be very telling.