A distinction needs to be made between what I suspect you mean when you say a "cloth mask" which is likely the equivalent of wrapping a t-shirt around your face and a pocketed cloth mask which acts as a frame for a hepa filter.

I've made two hepa cloth masks using online guides (I know, I'm like an expert now /s) for my partner and I and from my testing they filter out a non-trivial amount of undesirable particles. We use a pipe cleaner to add rigidity to the upper mask and form a better seal. I've lit a cigarette right in front of my mask and been completely unable to smell it. Does this offer us 100% protection? No of course not, is it better than not wearing one? Yes, of course.