I have found no clear connection between the cover and the title track on "The Royal Scam", and if you read the liner notes by Donald & Walter in the CD-remaster you get the feeling that they didn't have much to do with the way the cover came out:

"Our happiness at this particular point in time would be ultracomplete save for one thing - namely, we have not as yet found a cover shot for the album. ...
Luckily for us, we are in Los Angeles where, more than anywhere else in the known universe, bad taste abhors a vacuum, and before long we find ourselves staring into the maw of the most hideous album cover of the seventies, bar none (excepting perhaps Can't Buy A Thrill). Why are those buildings turning into reptilian horrors, or vice versa? What squalid back alley of the human condition is meant to be invoked by this contused nightmare palette? What manner of man - ill-shod, unshaven - dares sleep peacefully through this fearsome and repulsive protomorph?"