If you are in North America you can access the most resent revision of the Proposed APA standard on the Cream Legbar club's website HERE.
The APA standards books list a flopped over combs on cockerel as a Defect for ALL single combed breeds and varrieties, so you answer your question, yes the flopped over comb will be a problem, but only on the cockerels. The hens are supposed to have the comb gracefully flop to one side. Cream Legbars aren't the only breed with single combs that have this problem. They are more difficult to breed than most because their crest makes breeding erect combs harder. An old 1900's breeding guid for the Miorca talks about breeding strategies used in that breed to get the required flop on the hen and the required erect comb on the cockerels. Basically they would either breed hens with really small combs that didn't flop in cockerel to produce cockerels with erect combs then they would use the daughters from this cockerels with erect combs and even if the hen large flopped comb (per the Miorca breed standard) Cockerels that were breed from hen that had fathers with erect combs would also produce sons with erect combs.
If you are outside the USA you should reference the UK standard. It can be found HERE. It List a twisted comb on the cockerel as a Serious Defect, but not a disqualification for the breed. So cockerels with twisted combs could be exhibited there, but they would be penalized in the judging.
As far as the perfect Cream Legbar, these are the best images I know of. They were donated to the Cream Legbar club by one of their club members in 2013.
