Here is my take on masks.
Just from my experience from being around them and the couple minutes research I've done since this ordeal started.
Some good resources:
https://www.honeywell.com/en-us/newsroom/news/2020/03/n95-masks-explained
https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/face-masks.html
PPE Personal Protective Equipment
HCP Health Care Provider
Even a N95 or whatever mask will not stop all airborne particles.
They stop around 95% of basic dust sized particles.
It will catch most large droplets and water vapor.
Bacteria and germs are smaller than dust and viruses are even smaller than them.
Masks with a valve in the center make it easier for the wearer to exhale. May stop most water vapor but not airborne containments.
Might be acceptable for a caregiver but not advisable for a known infected patient.

Procedure masks, which are typically used for isolation purposes, may not provide protection against splashes and sprays. Should stop most droplets from patients. If care givers are wearing them around known infected patients maybe they should wear a face mask as well.
Possibly good for know infected and untested patients if supplies allow.
If both care workers and infected wear masks while in close proximity it greatly reduces the chances of transmission.
Current CDC guidance that not everybody wear a mask while in public is because there are not enough masks to go around, especially for caregivers. ( They said so much at today's and previous days briefings if you read between the lines) once more masks are available it will revise the decision and is currently evaluating it.
Yes wearing a piece of cloth like a bandana will be almost as effective as several face mask types. Maybe slightly less so than the procedural mask.
What is it most effective for is stopping droplets water born contaminates from the person wearing it to other people. (If you lightly dampened it maybe put a very small amount of isotropic alcohol that might catch some more material and kill it maybe somebody should look into that) similar to how you can put oil on an air filter.
https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/face-masks.html
HCP use of homemade masks:
In settings where facemasks are not available, HCP might use homemade masks (e.g., bandana, scarf) for care of patients with COVID-19 as a last resort.
However, homemade masks are not considered PPE, since their capability to protect HCP is unknown. Caution should be exercised when considering this option. Homemade masks should ideally be used in combination with a face shield that covers the entire front (that extends to the chin or below) and sides of the face.
Personally I would wear one at this point but all I see for sale are ones online from Asian counties.
I have a paint and pesticide mask I purchased for work and only used a couple times, i may start wearing that.
At that point I think you should also start wearing tight fitting glasses and gloves...dunno