The perfect application: 1. sponsor and applicant are close in age, but the man is the older one; same religion, economic background, race, ethnic background; first marriage for both; neither has any children; both are of a similar level of attractiveness; the applicant is from a first-world country.
2. They met in real life, their relationship developed normally, they got engaged after a year or so, got married at a big ceremony attended by both families and lots of friends, went on a honeymoon.
3. There is lots of evidence of contact and the forms are filled out exactly as required.
A complicated application: 1. the woman is older by more than 15 years; different religion, economic background, race, ethnic background; one party has been married multiple times, the other never; one or both parties have children; the applicant is from a poor country notorious for immigration fraud; the applicant is much better looking than the sponsor; the applicant can barely speak English (or French) and the sponsor does not know the applicant's language.
2. They met on-line. After 2 months, the sponsor goes for his/her first trip abroad to meet the applicant; they spend one week together and get married at city hall. No relatives or friends attend. There is no celebration, and no honeymoon. The parents of both are shocked and horrified - or don't know about the marriage at all.
3. There is almost no evidence of contact, because they used phone cards to call each other and didn't save any emails. There have been no further trips to see each other. The forms are filled out badly.