You'll need a so-called positive question record for the Curious badge and related badges.
A positive question record means you don't have too many closed, downvoted or deleted questions, overall. The formula is
(total questions - negative questions - closed - deleted)/total questions ≥ 0.5`
Questions that have been downvoted and closed and deleted count three times in this calculation!
You must have quite a few deleted questions, since those which are visible are quite positive on average. The ones deleted within the last 60 days are still visible in your profile, via the 'deleted recent questions' option.