Creo que lo puedes lograr sin recorrer todos los archivos de la carpeta
dim objFSO, objF, objFC, objFL
dim f1, w, h, c, strType, mostranom, folder, nomcarpeta, num
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objF = objFSO.GetFolder(Server.MapPath("../imatges_productes/"))
Set objFC = objF.Subfolders
For Each folder in objFC
nomcarpeta= folder.name
Set objFL = folder.Files
Response.write objFL.count For Each fl in objFL
num = num + 1
next
response.write nomcarpeta & "("&num &") <br>"
Next
set objFC = nothing
set objF = nothing
set objFSO = nothing