"I know"

6 characters Bad: 0.0085 - Good: 0.9915

EDIT: find a higher score than yours at one character less

"I went"

6 characters Bad: 0.0025 - Good: 0.9975

for 5 characters:

"I won" Bad: 0.0031 - Good: 0.9976

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at 4 characters:

"J ML" Bad: 0.0002 - Good: 0.9998