I said it once already, it is all about respect for me.
Does a 5 star review with emoticons is disrespectful to me? Not really. At worst, i'm just sad i couldn't get a proper review, but if the review is not fake at least you know someone genuinely enjoyed your work.. There's also children here. They can review however they want. I would delete however spamming reviews, for example when a reader publish the same review once or several times everyday.
The 1 star review, sorry to say it, but it is almost always disrespectful. I haven't received one yet, but i'm pretty sure the day i get one the review will have nothing worth to keep.
If the purpose of the review is to help the author to improve, then the rating doesn't matter. If i was reviewing a novel i would let the same rate as the current rating average, but with my detailed rating and constructive critics in the review itself. The author can delete it, since my opinion and advices have been conveyed.
If my purpose is to make anyone aware that this story is awful and no one should read it, i'm then reviewing for the readers. And the line between defaming the author and informing other readers is quite thin. I could keep such a review, if the reasons made sense as a warning for new readers. I could even pin it. But as before, respect first. The author has the right to decide how he/she feels about this in my opinion.
Don't be naive, though. If i decide right now to do a false constructive review, falsely respectful, but with the hidden purpose of libelling your story, i can really do some damage, especially for these new stories that don't have yet all these 5 stars spamming reviews to drown the bad fish.
In the end, this debate is endless. Want to keep 1 star review because you think it's fair, at your own risk. But in general, i think an author should pin a 5 star and 2,5-3.5 star constructive reviews(if he has some). It gives the pro and cons for a new reader under 2 differents perspective and that's an honest behavior from the author.