Modern art is one of those rather dividing things.
The guy back in the day who first put up a urinal, signed it, called it "Fountain" and proclaimed it to be art - was clever. Very clever. It provoked a reaction and got people thinking. What is art anyway?
People who do similar now, aren't as clever as him, I don't think. That's the thing though, that's my interpretation, and art is all in the interpretation. What do you think looks good, what sounds good, what makes you think, what disgusts you, what makes you uncomfortable, what intrigues you.
The way I see it, art is there for you to react to. It could be a pleasing recognition and admiration for the artist as you see a painting or sculpture which is very realistic, it could be just a general "mmm, nice" as the colours and shapes look good to you.
Is someone who purely copies real life as well as they possibly can an artist? Or just someone with good observational skills and motor control? If they start capturing unusual angles, or taking real life and abstracting it to look better, or worse, or just different - are they more of an artist now? How does that compare with a photographer? How about a photographer who does extensive post-processing?
As a kid I always sneered at modern art - I was always proud of my drawing, and didn't see merit in anything that I reckoned I could do - how come they got money and acclaim, and I didn't?
Sometimes I still do think like that, if I see something easy AND unoriginal. But real creative thinking is interesting. If someone puts real thought (not just "huurr, I'll wee on the loo seat and call it 'puddle', that's art, right") into something, and it's original, and it makes me react, then for all I care it's art.
Even if I hate it, that probably means it's taken me somewhere uncomfortable, which is likely to be exactly the intention of the artist anyway - so he or she is therefore successful.