"How can I make this SEDE query better?" (bad title finder)
Your query is well structured, and consistent, but there is one issue you have failed to incorporate.... not all bad questions have a user. When questions are migrated, or there's a user deleted, the question may have no link back to the Users table.

This requires an Outer Join to Users.

Additionally, I have found that CTE expressions are fantastic for aliasing column names. For example, both Posts and Users tables have an ID column, and you need to have Posts.ID and Users.ID in different places. Both also have a CreatedDate. When these aliases become long, and complicated, it bogs down the readability of the query.

Oh, about the readability, the case statement is dead code. Don't use code that serves no purpose, or, alternatively, "debug code" should be removed before deployment. If you cannot trust yourself to have the right conditions on the query, then you cannot trust yourself to have the right debug code either.

So, if you alias these values in a CTE, and use the CTE to make the Outer join neat, you can reduce your query to:

SELECT PostID as [Post Link],
       Score,
       PostDate,
       UserID as [User Link],
       Reputation
FROM BadTitles
LEFT OUTER JOIN Users on UserId = Id
ORDER BY Score ASC, PostDate DESC


OK, that's a cheat, because BadTitles is a CTE, but, the full query, using your expanded comments, is:

DECLARE @Question INT = (SELECT Id FROM PostTypes WHERE Name = 'Question');
DECLARE @Answer INT = (SELECT Id FROM PostTypes WHERE Name = 'Answer');

with BadTitles as (
    SELECT Id as PostId,
           OwnerUserId as UserId,
           Score,
           CreationDate as PostDate
    FROM Posts
    WHERE 
      /* Filter out non-question posts */
          Posts.PostTypeId = @Question

      /* Post not closed yet */
      AND Posts.ClosedDate IS NULL

      /* Generic title */
      AND (
            Posts.Title LIKE '%please%'
        OR  Posts.Title LIKE '%review%'
        OR  Posts.Title LIKE '%improve%'
        OR  Posts.Title LIKE '%better%'
        OR  Posts.Title LIKE '%how to%'
        OR  Posts.Title LIKE '%how can i%'
        OR  Posts.Title LIKE '%how do i%'
        )
)
SELECT PostID as [Post Link],
       Score,
       PostDate,
       UserID as [User Link],
       Reputation
FROM BadTitles
LEFT OUTER JOIN Users on UserId = Id
WHERE (Reputation IS NULL OR Reputation &lt;= 500)
ORDER BY

  /* Lowest scores first - Change to DESC if you want Highest first */
  Score ASC,

  /* Newest first - Change to ASC if you want oldest first */
  PostDate DESC


Note that this produces an addition hundred or so questions from migrations, etc.