Tack cloths are impregnated with wax so that loose particles will stick to the cloth. They work VERY well as long as you wipe very gently. Don't rub them or you'll get wax on your model and the finish won't stick.

When covering with an iron on, I use my shop vac with a brush and an air compressor to remove dust. No tack cloth because it isn't necessary.

When painting I do the same thing but I give a final wipe with the tack cloth to remove any dust that's left.