Nice dig.
The nation's leading experts are recommending the widespread use of masks -- not to protect the wearer from acquiring the virus -- but to help prevent those with the virus from spreading it further. For example, coughing with a mask on probably reduces the distance of the droplets. If you're within radius of the droplets though, and have a mask on, it probably wont do shit. My reading comprehension taught me that cloth mask filtration with virus is almost 0%.
"Self-contamination through repeated use and improper doffing is possible. For example, a contaminated cloth mask may transfer pathogen from the mask to the bare hands of the wearer. We also showed that filtration was extremely poor (almost 0%) for the cloth masks. Observations during SARS suggested double-masking and other practices increased the risk of infection because of moisture, liquid diffusion and pathogen retention"
"In the interest of providing safe, low-cost options in low income countries, there is scope for research into more effectively designed cloth masks, but until such research is carried out, cloth masks should not be recommended."
To answer the previous question -- no there was no control vs effectiveness against no mask at all. So, is throwing a bandana over your face more effective when walking around walmart? Maybe, maybe not. If someone with the virus sneezes near you... no, its not going to do shit. If the virus is on your mask, is it more likely to stay there due to increased moisture retention? Yes. If some dumbass with the virus is out in public and wearing a mask, will it slow their infectious rate down? Probably. Could people walking around with masks now have an increased false sense of security, and start to relax their hygiene and other counter measures? Maybe.