I believe one of the main jokes of the story is precisely that the mc sees herself as a "scumbag" (as shown in scenes where, after being harshly scolded by her strict parents, she mutters angrily to herself "Yes, yes, I'm a scumbag, I get it!") while in fact she's one of the most pure-hearted characters to ever grace a yuri manga. Her only real faults are a little bit of childlike selfishness and laziness; and we have already seen that, if it's for the sake of someone she loves, she will become selfless and hard-working without a moment's hesitation.
Honestly, I rather like how the chapter titles doggedly remind us that the mc is supposed to be a scumbag. I enjoy this type of tongue-in-cheek humor. It's like how F3, from episode 2 onwards, was full of comments and sidenotes constantly reminding us that Hiroe's mom and sis were not her real biological mother and sister no matter how different the actual facts in the story were.
In any case, as I mentioned in a previous post, if anyone wants to read about a real scumbag of a yuri heroine, I recommend you try this manga. Toudou-chan won't let you down, trust me on that one.