WiFiJeff, exactly. A single-diaphragm omni condenser microphone is a pressure transducer. Pressure transducers are relatively insensitive to vibration, solid-borne sound, wind, breath noise and proximity effect.
All those problems are characteristic of the other type of transducer, which are called either "velocity" or "pressure gradient" transducers depending on who's calling. Directional microphones always include some degree of this kind of functioning, and the farther you swing toward figure-8sville, the more these problems manifest. All other things being equal (though they rarely are), a figure-8 will have more sensitivity to wind, popping on close-miked vocals, solid-borne sound, proximity effect and whatever else was on that list.
It's a spectrum--wide cardioids are the least affected because they're the closest to being pressure transducers (they might be 60/40 or 70/30). Then cardioids, then super- and hypercardioids. Finally figure-8s, which are pure pressure gradient transducers.
The omni setting of a variable-pattern dual-diaphragm microphone is actually two back-to-back cardioids added together, so it acts more or less like a cardioid in these respects. The proximity effect may cancel out to some extent but there is still some.
--best regards