Here are the top 5 recurring objects or themes that usually appear in artworks:

1. Overused fonts

Just a while back, it was Helvetica. In bold.

Helvetican't poster from zazzle.com

Keep Calm and Carry on Poster from keepcalmandcarryon.com

Now it’s Gill Sans, thanks to this poster.

2. Found objects.

Fountain by Marcel Duchamp, via Wikimedia Commons

So, since Duchamp challenged the whole notion of art by placing a urinal on a pedestal, it seems like the idea that one man’s trash is another man’s treasure has caught on with many other artists. Dadaism seemed to set the stage for commodity sculptures, trash art, and other forms of contemporary art.

3. Shock Tactics.

Piss Christ by Andres Serrano, via Wikipedia

Artists often employ this tactic by taking a stab at controversial issues, usually religious or sexual. A good example would be Piss Christ – the infamous photograph by Andres Serrano that actually won the Southeastern Center for Contemporary Art's "Awards in the Visual Arts" competition.

4. The inclusion of bodily material. (Think: hair. Fingernails. Blood.)

So Serrano included his own piss in “Piss Christ”. Manzoni sold his shit in cans. Quinn used his blood to make a frozen cast of his head. Lennie Lee performed using feces, blood and vomit… Do we see a trend here?

5. Self portraits

I guess the easiest way you could get a drawing model would simply be to practice drawing on yourself. Nothing against it, but commonly done.

That said, we aren’t saying it’s wrong to include any of these elements in art, or that artworks with these themes or elements would be “bad art”. It’s inevitable that ideas are reused, and as along as concepts are well rationalized, why not.