Never used it, Ed, but my guess is if your ground is claggy then 'yes' the mud will be squeezed through any perforation. I wonder if you'd be better off getting the whole of that area ready for planting out and when the weather gets a bit fairer, create your beds and lay your plastic path then. The mulch/compost you use on the garden would also help with the clay problem on the paths. If the beds are already in position then why not try bark under the plastic? I sometimes use old carpet for pathways but I only put it down after my ground has firmed up a bit.