There are a lot of subjects that are used often, but if someting is well done or has a fresh spin on it, I will still appreciate it on it's own merit.

How about shirts with a heart on ? Has anyone done that yet ?

I agree with that.. so maybe the question should be:
Which subjects are use so often that it's hard to make a fresh design with it?

The prof is right if you have a concept of real merit don't let it put you off . Any tired theme can excel if it has a fresh spin.

However, having said that these are some over used Threadless themes - Octopi, penguins ( especially attempting to fly), hearts, obvious puns, short sighted hedgehogs shagging hair brushes, upside down set of instructions / tables etc and talking excrement.

Usually if you have a sucessful concept you have a whole slew of copy cat designs for the next month. If you are unsure if a theme has been done before type into the blog search under designs and see what comes up.

Hmmm...

There's so many heart and skull designs, those are hard to use without looking cliche.

Lots of voters get tired of FWF (food with faces), but there's been a lot of prints using them, too.

Do you have a concept in mind you'd like to try out?

Spam also speaks true.

Yeah tell us so we can copy it and sub it at the same time

BTW case in point - rainbowsucker was an original concept even though rainbows are in every other sub. I gave it a 3 @ the time.

I also see a lot of designs with soft colours.. why not more bright(or even neon) colours? Personally I think the brighter the better, but that's probably just a fase in my life.. after black, skulls and rabbits!

@professorE
I do have a concept in mind, but that's for the long run.. at the moment I'm having another design up for critique..

...just found out the concept I had in mind is also already done before.. It's hard to come up with something really nobody has done yet!