[J105C]

Well if you know the image link you can simply use the Replacement Variable Manager to change the image URL.

AdminCP>Styles & Templates>Replacement Variable Manager

Then select, 'add new replacement variable' next to each active skin and copy the ENTIRE or PART of the 1px image URL and paste it into the section, 'Search for Text' then enter a new image URL into the section, 'Replace with Text'.

That should fix ALL the 1px images from ever showing. If there are TONS of different trailing image file names I would create a new replacement variable for the base domain name to result in a red X.