Bad reviews are never a nice thing to receive - but I do think there is a way to soften the blow that they deliver.
From what I have seen there are 3 types of bad reviews you can receive (if you have any more, please add them below) and each one requires a different response:
1. Complaints about formatting and grammar - it is terrible when you receive this sort of review as it questions your professionalism as an author. However, it is a problem that can be fixed - you can re-work your manuscript or hire a proofreader and/or someone to format your book and correct these problems.
2. Complaints about the price - with the 'brand authors', you will often see readers leaving one star reviews because the e-book costs more than the print version of the book. But with self-published authors, I have found readers leaving negative reviews because someone has price a short story for $5 - make sure your writing is reasonably priced - and if you are selling shorter fiction make sure you state that it is a short story several times in your Product Description so your reader does not feel like they are being mislead.
3. Complaints about the quality of your writing - this is the toughest of the three as it questions your actual abilities as a writer. To make your self feel better, look up your three favourite novels - I am pretty sure you will find a number disparaging views for these books. Just as an example, I looked up Moby Dick on Amazon UK - I was shocked to see that Melville's masterpiece has 14 1 star and 15 2 star reviews out of 112 reviews.
However, if someone critiques your work rather than just saying, 'This is really crap, I demand a return', it would be foolish not to take their criticism on board and use it to ensure your next book improves.
Of course, there will be times when a negative review mixes all three of the above, but as writers we need to believe in the work we put out and be as thick-skinned as possible (as hard as that can be).