An inexpensive microphone can publish a frequency response that looks as wide as a professional one and still sound obviously worse. The published number is not measuring what matters.
Frequency response is the least useful figure
A stated range describes which frequencies the capsule can register at all, not how evenly it registers them. A microphone can cover the full band and still be lumpy across it.
Manufacturers rarely publish the tolerance that would make the number meaningful. Without it, two microphones quoting identical ranges can differ audibly in the region where voices sit.
The useful information is the shape of the curve, and where it is deliberately lifted or cut. That shaping is what gives a microphone its character on a particular voice.
Self-noise sets the floor
Every microphone generates a small amount of noise of its own, a hiss present before any sound arrives. On quiet sources this floor is the limit on how clean a recording can be.
Recording a soft voice at a distance means raising gain considerably, and the noise floor rises with the signal. What sounded acceptable in a demonstration becomes a wash of hiss in a quiet room.
This is the specification most often omitted at the lower end of the market, and it is the one that separates a usable recording from an unusable one.
The polar pattern does the room rejection
How much of a room a microphone hears depends on its directional pattern. A tighter pattern rejects reflections from the sides and rear, which is what makes speech sound close rather than hollow.
Cheap capsules often have patterns that hold their shape only at some frequencies. Low frequencies leak in from all directions, so room rumble arrives even when the voice is on axis.
That leakage cannot be removed afterwards. Reverberation is baked into the recording, and processing that reduces it also degrades the voice it was meant to rescue.
Handling and wind are mechanical problems
A capsule mounted rigidly transmits every touch of the body and every cable movement directly into the signal as a low thump. Suspension mounts exist because the problem is structural.
Wind is worse outdoors, where even light air movement across the capsule produces distortion that no filter fully removes. Adequate shielding often costs a meaningful fraction of the microphone itself.
Placement outranks the purchase
Halving the distance from the source raises the direct sound substantially against the room, which is a larger improvement than most upgrades within the same class deliver.
A modest microphone placed close in a soft room will outperform a better one placed far away in a hard one, which is why the room and the stand deserve budget before the capsule does.