As poor as they are, they're the objective measure that we have. Over the next few days we'll see how the debate plays out in the "real" opinion polls.
You're claiming a Hillary win based on what ? Your own (highly partisan) impression ? A few talking heads in Washington and the media ?
If the Brexit vote taught me anything it's that the media and pundits have become detached from the electorate. The media and pundits, the comparatively impartial ones at lest, are making their judgement based on facts and logic. Large parts of the electorate do not do that any more (if they ever did).
Well Bernie never had the level of support in the polls that Trump has. Going into the debates he was within the margin of error. A perceived "win" in the debates could tip him into the lead.
Here's a short quote from a fivethirtyeight commentator:
http://fivethirtyeight.com/live-blog/first-presidential-debate-election-2016/
In essence that may be all he needs. A third term for a party is comparatively unusual in recent times - moreso for the Democratic Party - so the deck is already stacked against them. After 8 years people typically want change and Trump has done just about enough to allow those who want change to vote for him