[snip] fabric making contact with the mics.
The type of fabric, the microphone surface that it comes into contact with, and the way they interact with each other are all key. The other primary factor is the sound level of the recorded environment. Generally there is little problem when recording loud program material, while fabric interaction noise can become a significant problem when recording very quiet material.
First, the fabric itself must be sufficiently transparent in the sonic sense so as not to muffle the sound, and the microphone mounting method must also sonically transparent, allowing for an unobstructed sound path. Those two aspects refer to the simple 'static' non-moving/non-shifting condition, with no relative motion between the two. Just getting those aspects right may be sufficient for louder material. If only it was that simple for the quiet stuff..
Secondly, there will be some degree of handling noise created by movement, sometimes incrementally small movements which are otherwise undetectable, such as tiny movements from simply breathing. That might be traced to the fabric rubbing against the microphone itself or its attachment, or cables moving and rubbing and transmitting noise through the cable structure to the microphone. Different fabrics behave very differently, some which are otherwise beautifully transparent to sound are mechanically very raspy and tend to make more noise when shifting slightly. Foam windscreens tend to make a lot of rasping noise if the fabric actually rubs across them and so can some mic grid screens and/or sharp edges. One approach is to try and anchor the fabric and mic so they don't shift relative to each other and rub, but that can be difficult to achieve in practice. I find anchoring the mics in place and providing a smooth surface for loose fabric of the appropriate texture to come in contact with tends to work well.