When I retire buckets (havent done so yet after a few years) they will:
1 - be repurposed to hold grain. A Home depot 5 gallon bucket holds around 25 pounds of grain. A 6.9 gallon bucket should hold around 34 pounds of grain.
2 - hold pre-mixed Star San. Currently I use a 5 gallon Home depot bucket, but every time I make a new 5 gallon batch (a few times a year) the bucket loses foam or splashings when I spill it back in.
3 - I brew in a bag and catch the crushed grain directly in my bag. If I were to double crush (which I wont, I'd just crush tighter) then a bucket might be useful.
The only thing that goes in my buckets are:
plastic stirring spoon
plastic auto siphon
plastic bottle filler
plastic tubing
plastic spiggot
After using them I clean them with a dedicated sponge and dish soap so they dont have stuff drying in them for any length of time. (Maybe 30 minutes while bottling). I also sanitize them before and after using them. Sometimes I use Star San and Idophor on them (at different times), just becaus eI have the solution mixed.
My buckets smell ... like beer.
I may consider retiring them at some point, but they are unscratched and I haven't had any infections.