<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Should the dealer accept some, or all, of the responsibility for this? </div></BLOCKQUOTE>
Sorry to hear about the delamination on your new to you
trailer. I did a search on 'delamination'
and had 124 hits, you may want to read up on the issues others have posted about concerning this problem.
It might be in your best interest to obtain the name of the person the dealer obtained the trailer from and ask them if they were offered less on it on a trade in due to its delamination problem. If they were and the dealer denies any knowledge of the delamination you might want to ask why they would offer less for it from the previous owner due to a delamination problem and then pass it off to you, denying any knowledge of the pre-existing condition.
It's doubtful the dealer took it in trade and didn't notice the delamination, possible but doubtful.