Help - really bitter Winter Festival Squash

I've grown Winter Festival for the last 4 years with no problems until this year (the problem this year being I had to plant them out late and even they they were very slow to get going.)

I don't know the answer to your problem, but wonder if it is one of the two possible issues discussed on here recently regarding cucumbers:

http://chat.allotment-garden.org/index.php?topic=83067.msg926984#msg926984

If you have other cucurbit varieties nearby cross-pollination is a possibility, although the usual understanding seems to be that only the seeds would be affected by that (which you don't eat, of course.)

Sorry I can't offer anything with any more certainty or usefulness than that!

Thanks for your responses.

I reckon they've probably had more water than previous years as I've been so much more conscientious because of the dry conditions and I do love my squashes.

Maybe I'll just have to approach the smaller ones with caution - 2 of my 6 plants have thrown out smaller fruits, but as well as the large ones, so no apparent consistency in that either.

It's a lot to ask, but if anyone has grown these this year would they be prepared to taste a small amount of uncooked squash to see if there's any bitterness there before cooking? 

I'll understand if you're not keen (it's a lot to ask for a complete stranger who hasn't posted on here for ages but used this forum to get me up and running with an allotment and can safely say my crops are normally fabulous because of all the info on here), but it might be a way for me to save all that time and effort in preparation and cooking something which is going to poison me!

Someone said that squash didn't do well this year because of the generally low night time temperatures. Certainly mine were poor, quantity wise - I haven't tried eating the ones that actually grew yet.

This may be the answer
http://www.mastergardenerssandiego.org/faq/item.php?ID=19.

Some are quite bitter until they are cured or ripened properly, either on the vine (preferably) or on a sunny windowledge, so that the sugars develop.