It's not rare that a lesser instructed person questions an artist about the aesthetics of his work. And lesser rare it is to question it on the grounds of his (or hers) own taste, misleading the two concepts (aesthetics and taste). There is a lot of artistic work scattered around in museums and exhibitions which I also definetely don't like but that I see myself forced to agree that, damn', they are art! And moreover, evolved art!
But what do we speak of when we speak about aesthetics?
In any dictionary we can find a first definition for aesthetics as it being the branch of philosophy that studies the beautiful; or the science whose object is the judgement of values refering the distinction between the beautiful and the ugly. The etymology of the word however tell us a more embrancing thing: [from the greek] aesthesis, the perception by the senses. This is a definition transversal to several cultures and whose object - the beautiful - it's the quality that causes an emotion, i.e., the attribute that qualifies the objects and the works tha are offered to (our) perception. In the artistic domain those objects or works don't require understanding until subjectivity (i.e., the interpretation, the personal sentence) is requested by the appraiser of those works or objects. For example: a coffee machine and a painting from Cy Twombly (so it can be very abstract, so to speak) are offered to the perception of an individual. The coffee machine does not request any subjectivity (at least not immediately) of the individual because it's of common sense what the coffee machine looks like and what it does. The Cy Twombly painting however, and because it's abstract, immediately requests the subjectivity of the observer: he will have his very own interpretation of what his eyes see and most probably it will be very different from other observers interpretations of that same work. And it's after that subjectivity has been requested - and therefore, the request of an emotion - that the work of understanding a work of art begins.
In art the beautiful proposes works that always aim to please the appraiser even though many of those times they are unpleasant. It is what I often call The Pug* Principle: they are so ugly, so ugly that they become beautiful. Therefore it's assumed that there is an intention from the creator of the work of art in providing an aesthetic experience even though sometimes is is not of our liking. I may not like a Dalí painting but the way such work embodies its aesthesis lead me to admit that it is art.
* Pug: breed of dogs originary from China (they can been seen here)
To know more:
[From a dictionnary of philosophy from which i've had access through photocopies but that unfortunately wasn't given me to know the original edition]