Oh, oops. I meant there's nothing to indicate she's the rampaging raging ANGRY type of psychopathic killer. IE, the way fandom portrays her.
Never said she wasn't a "perfect and elegant" cold hearted killer (which is also psychopathic, if I have the definition of the word correct, but in an entirely different sense). Fandom however (almost) never portrays her as that. Instead we always see her spazzing out about pad jokes or catching Mei Ling sleeping on the job.
...in fact, fandom seems to stay away from touching the whole "Sakuya murders humans" thing in general for some reason. Probably because it's too grimdark for the Touhou series.
On that tangent, I'm not sure how serious Sakuya was about killing people, given that tons of youkai claim to eat people but that's just posturing. The context of Sakuya's quotes indicates she too might just be posturing (then again, maybe she's serious, too.)
Flandre's profile says her food is "made from living humans". And that they just "look like harmless foodstuffs as cake and tea". This could be interpreted as actual human meat being made to look like harmless foodstuffs, or maybe they just have blood mixed in. It's interpretable either way, I guess, tho IMHO more likely the former interpretation (actual human meat)
In Perfect Memento in the Strict Sense, it's stated that the vampires (presumably Remilia and Flandre) have a contract with the youkai to get humans from the outside world for food, and it's stated these humans dissappear from the outside world "forever" being written off as suicides, etc. There is probably room to believe that the humans are simply drained of a little blood, although me personally in my own interpretation, I believe they actually get killed and Sakuya cooks them up for Flandre (her food is made out of LIVING humans. Fresh meat!) and the rest of the youkai in the SDM. Akyu also states there's no worry about Mei Ling eating you (the human reader) because "her meals are provided by the Scarlet Devil mansion", which I interpret as meaning Mei Ling won't eat human you because she gets plenty of human meat from the Scarlet Devil Mansion.
Perfect Cherry Blossom's prologue also states that youkai chef teams go out to get humans from the outside world (and setting things so it looks like they were suicides, etc) to eat. I'm not sure if Perfect Memento retconned that into the vampire contract, or if the general youkai population of gensokyo gets humans to eat that way, themselves (while also doing that for the vampires too due to the contract), PCB's prologue would thus imply certain other youkai besides just Yukari can come and go from the outside world at will.
Fandom practically never touches on any of that, though. Maybe it's too grimdark for the Touhou series even if it's canon (probably. Again, slightly open to interpretation and translation issues). The fandom is willing to grimdark a lot of Touhou, but cupcakes made out of people and such a human-ish youkai like Mei Ling as an actual human-eater is probably a bit much for a lot of people (tho despite being a very human-ish youkai, it's canonically confirmed Mei Ling herself is fine with eating humans, as shown by her EoSD dialogue, even if she's just joking that the rules should allow her to eat shrine maidens).
....ARGH, lots of people beat me to it.
Oh, forgot to mention. Reimu being greedy is also canon, although like Mei Ling's laziness, the extent is debatable (Me personally, I think she's mainly just greedy to the point where she needs/wants her shrine situation to be improved. Right now almost no one visits and that's probably semi-depressing for her sometimes when she bothers to care about it). It's explicity stated in one of her story paths for UFO that she's going after the treasure ship for the treasure. And of course, you can't really ignore her insistence to Sakuya in IaMP "The offeratory box is over there!" And then in Wild and Horned Hermit Reimu is practically spazzing with glee at the merchandising opportunities that Kanako and Suwako's latest scheme might bring her.