When I look at the database I see a few photos that could have used better processing, but I hardly see any that appears "photoshopped". Photoshop is simply a tool, so I would personally rather use the term retouched.
If a photo was truly professionally retouched, you would not be able to judge from the foliage color if the bloom color is accurate or not. If you want to retouch a photo to make the flower look more unique or colorful then it would be very unprofessional to alter the foliage color in the process. Very odd looking foliage(and we have already established that there can be some natural variations) could certainly be the sign of an amateurish attempt at enhancing the appearance of a flower, but is far more likely to be the result of not setting the white balance correctly for the lighting situations.
Most people believe that leaving the camera on auto everything will give you accurate and true colors. This approach could work in some situations such as harsh sunlight, but is highly unlikely to succeed in every light situation.
I have long been looking for an easy to read article that explains the importance of manually setting the white balance correctly and I think I finally found one. It's for video and not photos, but the reasons for adjusting white balance are exactly the same.
Required reading: http://schoolvideonews.com/Vid...
Still photographers can use a gray card, a color checker card or adjusting the white balance after the shot in various software to do the white balance.
Also, before correctly assessing colors a monitor needs to be of good quality, not too bright and properly hardware calibrated. Most users on a garden forum is highly unlikely to own such a monitor, so everyone will view a photograph a little differently than the next. Some might even resort to editing their photos to have them matching their uncalibrated monitor, but this is lack of knowledge, not something anyone would do to mislead.
