OK theres a pretty simple trick to seeing if theres crud in the bottom.
Get your oil
pump you suck your engine oil
Remove the fuel feed pipe into the bottom of your tank.
Insert the oil pump pick up line right to the bottom into a corner. Suck up the fuel. Check for debris. if it blocks with gunk on the bottom tip of the tube you have chunky stuff.
If no debris you dont need to clean the tank.
If you wish to clean the tank buy/borrow a fuel pump
and suck all your fuel out. Put in a few gallons of clean fuel and suck again paying particular attention to the corners.
Refill with nice clean fuel.
Use old fuel to make Molotov cocktails for your next terror attack.
I paid a guy with fuel pumping kit. he was better able than me to get all the gunk out. He was worth the money
and when he polished the fuel the price
got to be very low because of the fuel recovery.