I tried this with your code and got the same results, i.e. always yes.
So to trouble shoot (and see the value of 'searchable' I tried this in my resource:
<p>
this is searchable: [[*searchable]].
</p>
Search: [[YesNo? &value=`[[*searchable]]`]]
And this worked, I got yes or no depending on the search setting, with searchable = "" or "1"
I have no idea why this made it work at the moment
played with it a little more - very strange, but I don't have time right now to follow up.
[ed. note: whistlemaker last edited this post 14 years, 7 months ago.]