Improving the performance of procedures showing warnings for implicit conversions
sp_BlitzCache will break down implicit conversion information for you, for seek affecting converts. 

For example, with this query (for brevity):

DECLARE @butthead SQL_VARIANT = N'your mom'
SELECT COUNT(*) FROM dbo.Comments AS c WHERE c.Text = @butthead


And this plan, it'll return results like this:



If you click on the implicit conversion info column, it'll give you a break down of what happened where:



So while it doesn't search your plan cache specifically for that issue, it will give you your most resource intensive queries and warn you when implicit conversion is a problem, and then break down the details.

Hope this helps!