I used to be pretty juiced on this marker. Great compact size, plastic body so its quiet, and a perfect nib size wise (fragile as f*ck tho) However the last 2 I've had have had the same issue, with various inks. As others mentioned, the valve gets stuck down or halfway down and the marker loses a lot of functionality as a result.
I've had bad experiences with:
Not sure what ink this marker is made for, maybe the molotow high solid paints would perform better but IMO those are not suited for tagging. If I ever get another it will be saved for sketchbook use.
Hands down one of the best empties on the market. Uni paint/Smash KO nib but its 2x as compact while still staying full for a good amount of time (probably the same as a uni or KO considering those come like a third full while you can fill these almost to the top).
Like another reviewer said, its true that the nib is not the MOST durable thing but what are you expecting from a 4-8mm nib???
I use it exclusively for tagging and the nibs last a good while. I fill this bih with speedflow or coversall depending on what I have with a little pilot if I feel like it or want to save the good stuff. Pick one up along with some nice black ink.. and some bullet tip replacement nibs...you wont be disappointed.