[rozap]

Leaky brake hydraulics aren't anything to mess with, you should fix it or have it fixed soon. It could be something (relatively) harmless like a common hydraulic system shared between the clutch and the brakes (VW uses this design, perhaps others) in which case a failing master/slave cylinder in the clutch could cause the level to drop without compromising the brake system, but even then, soon you will be clutchless. But barring that unusual circumstance, the brake system is compromised and that's dangerous.

Otherwise I agree with what you said, and the best way to tease those details out of a candidate is to have an informal, personal discussion like getting lunch or getting beers together. But that's not enterprise scale.