Should any icon also indicate (by background or shading) the percentage of good reports?
0-25% no background
25-75% half background
75%-100% full background
From the report page:
Do not worry about your accuracy too much; one accurate report is worth many inaccurate reports
Which is why I doubt theymos would want to put any sort of emphasis on the percentage of good reports, even if it's just badges.
Still, there is a difference between 300 reports where 1/4 are good, and 3/4 are good. That difference increases at 2,000 reports...
I agree a small number of inaccurate reports don't mean anything - but should someone who posts 1,000 spam reports wear the same badge as someone who posts 1,000 accurate reports?
I don't theymos is planning to include bad or unhanded reports in the badge calculation. From OP: