According to Donald Maass, there are three types of protagonist: The regular guy, the heroic guy, and the dark guy.
Fair enough. But no matter what sort of romance novel you enjoy reading, there are some people you'll never see falling madly in love.
Like the procrastinator. Sure, that's a nice regular person sort of foible -- but you're never going to read a sentence like, "She really ought to call her boss back, but every time she picked up her phone, she just couldn't resist playing 'Angry Birds' one more time." You especially aren't going to see that sentence if you, as the reader, know that the procrastinator risks losing her job. You're more likely to volunteer for root canal than follow the self-destructive peril a hard-core procrastinator can get into. Not to mention the adverse psychology of reading a book that is constantly reminding you that that are a lot of other things you might be doing...if you weren't reading that book.
And regular guy professions have some natural exceptions. Anything that makes the worker smell bad when he comes home -- that's out. Fish processor, garbage sorter, mortician (or medical examiner) -- I really think those are non-starters. We know we need to have all six senses in the deep POV third person, but I don't want to read a richly evocative account of what these workers smell like when they get home after a long day at work.
Heroic professions include cops, firefighters, surgeons, and so forth. Not an exterminator. Oh, hey -- they can find themselves in some truly scary situations and if they can help out a homeowner with a serious termite infestation, say, or snakes under the house, they're heroes. But I don't want to read about them dealing with any -- and I mean any -- of the things exterminators have to deal with. Besides, in my experience all exterminators are named Stan. That's simply not a hero's name.
Dark protagonists have something twisted or conflicted in their past, their present, their psyche, something. They're tortured, or misunderstood, or desperately in need of help -- possibly even help the heroic love interest can provide.
But in a romance novel the dark protagonist will not be a hoarder, or even people with garden-variety obsessive-compulsive disorder. It's shame, too, because such a person would be a lot of fun to write about...just not fun to imagine in a romance. A little clutter does not a hoarder make -- the writer would have to pile it up, carve paths through it, fill entire rooms so that the doors no longer opened. Very conflicted, very twisted, very very dark. But not easily lovable.
Same thing for the crazy cat lady. If you need to describe kitty litter boxes in the double digits to round out her personality, chances are she's got a few dozen too many furry friends and won't have room for a nice normal guy -- heroic or not -- in her heart.
Here, then is the quintessential "no way José" meet cute: Pat, the county's animal control officer, arrives to help out Chris, who has been putting off doing something about the ever growing collection of rats at home...
Ugh. I've managed to skeeve myself out just writing this post. Here's something to make us all feel a LOT cleaner! (Click on him to see the original photo, which I cropped to make slightly less NSFW.)