Build the sql in vba omitting the null fields, assign it to a querydef then open the query as a pdf?
Not much control over how it looks (images, headers, etc) but should take care of the problem of controls with no data.
@stalk: typical Access report has controls that are always there. As noted, they could be made invisible if empty via code, or perhaps if you want to put conditional formatting on 20 (40?) controls. Likely there'd be gaps because of the invisible ones. Building a report on the fly would be a horrendous undertaking. Better to normalize as it would hurt far less and you're likely to run into more trouble like this as you go if you simply create work-arounds.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.