It's best to have the cleanest tank you can, but you would be suprised at what collects in the tank over the years....... I "modified" my fuel sending unit so I have a flexible line running to the rear of the tank. I did this because I like balancing my machine on the tail and with a low fuel level the stock sender was left in the air and the motor would stall. During my first ride with the new line all the bug, stick, twig, leaf parts that got dropped into that tank over the last 24 years got sucked into the filter. I think I cleared the filter 3 times before the tank stopped sending junk, the previous owners didn't run their canned fuel through a filter funnel like I do........
I also had to run extended lines, for my bilge pumps, up around the carbs because the pumps reversed their action at low throttle with the rear of the hull pushed under water and the hull would flood.