gepo optimizer question

I have a question with regard to GEQO optimizer of Postgresql.

For complex queries with over 12 tables in a join, (12 is the default
value), the Postgresql optimizer will not use the dynamic programming style
optimizer. Instead, it uses genetic algorithm to compute a sub-optimal query
plan. The reason is that GEQO takes sub-seconds to find a query plan while
the DP style optimizer will take minutes or even hours to optimize a complex
query with large join degree.

I am wondering if anyone here ever had complex queries that the GEQO fails
to work properly, i.e., finds a terrible query plan as compared to one
found by DP optimizer (by forcing Postgresql always uses DP). This is
important to me since I am trying to see what type of queries will be worth
spending a lot of time doing a thorough DP optimization (if it is going to
be executed again and again).

thanks a lot!