Hi folks,
While working on http://www.slangenboren-online.nl/, I had the exact same issue as described in the first post, and I think Adrianmak's solution works.
A little more in detail: After not being able to modify the Catalog products list anywhere within Drupal or Ubercart, I started to look into the Ubercart source code. It seems that the Catalog products list is hardcoded in file ubercart/uc_products. E.g., around line 925, the n/a-string is mentioned that is displayed when there is no image.
As Adrianmak pointed out, it is an option to hack your solution there.
Regards,
Jeroen.
