The lensing would show grouping wouldnt it g-man?? and if the dark matter was evenly distributed (as it should be) then this wouldnt show as grouping. (I assume). So it would be very difficult to detect if at all. If it has mass, as the theory stands, and is evenly distributed it would be like trying to find colourless liquid in water I would think.
cheers bullet
bullet1968
"A Darkness at Sethanon", a book I aspire to model some of the charcters and scenes