It's rarely a sham these days.
That's for two reasons:
(1) The rules are being more strictly followed (my wife's cousin went through an extensive process despite the fact that her first marriage met exactly none of the criteria for a Catholic marriage) and
(2) Probably 50% of Catholic marriages or more involve spouses who have defective intent.
It is very difficult to argue that Ted Kennedy or Joan Kennedy, who was raised in Riverdale in the 1940s and went to Sacred Heart, did not understand and agree to the conditions of a valid Catholic marriage.
Thanks to "the spirit of the Council" very few young Catholics are versed in Casti Connubi.
Seems to me then that the Church ought to make sure that anybody they marry fully understands what is involved.
Maybe they should do like the surgeons and put together a "fully informed consent" video and then have the blissful couple sign a bunch of forms. :)
Unless of course the unexpressed purpose is to leave a door open for a future annulment.