I think the "Results" are a combination of all three mentioned. Right now, there are 12 contestants. As Robin said, with people voting in so many diverse directions, the votes are too diluted.
Then you have one contestant whose mom (may have) brought a considerable faction of voters, not usually voting/viewing the show, and that changes the numbers.
Third and finally, I think the producers, while generally letting the show run unimpeded, ALWAYS retain the right to override, overrule and make the final decision
for the best interest of the show. I can't imagine ANY corporation, company, entity of a multi-million dollar business who doesn't/wouldn't maintain the right of final decision & control. You actually think the producers will & ABC will knowingly LET something topple the show, (a business,) if they can stop that from happening?
Donald Trump & the producer, Mark Burnett does it on
The (Celebrity) Apprentice, shows. It even states that at the end of the shows. (I don't know about Burnett's other shows as I don't watch them.)
Top Chef, says the same thing, that final decisions are made by the judges AND the producers. Judges overseeing court cases, can override and set aside the verdicts of jurys if they feel it is in the best interest of the defendant/case. Heck, even the presidential vote is ultimately decided by electoral college, NOT popular vote. The founding fathers did not want to leave it up to the general public. (Just using it as an example, not meaning to set us on a political discussion.)
I have a strong suspicion that on
The Bachelor, the year that Jason first picked Melissa, then dumped her for Molly, the producers *could* have persuaded him into choosing Melissa, telling him he can later say he made a mistake and pick Molly and all will be well in the end. Remember, it was, "A
Bachelor first, in the history of the show." How wonderful for ratings & controversy for the show.

What no one counted on what the incredible backlash that it actually caused instead.
The irony is, (IF it really went down that way,) the show would have actually has it's SECOND marriage from the show, instead of the short-term ratings it got. I have rarely heard the show or Chris promote, after Jason married Molly, how there was a second wedding after all. That, while he chose the wrong one initially, he DID end up meeting his true love on the show, after all. If it was all a harmless mistake, you'd think the show would be advertising the heck out of a SECOND marriage happening because of the show. Instead, it's mostly swept under the rug like some b****** child, no one wants to acknowledge.

I think the
producers made that choice and Jason, has naturally been furious as HE was the one who received all the back-lash & hatred, and because of non-disclosure agreements, will never be able to really clarify what happened.
I also think on Emily's season, she was going to let one guy go, but he interrupted her final rose decision. When she came back and ended up letting him stay, she was NOT happy with either him or the decision. It showed. I *think* from the time she talked to the guy, to walking back into the room, the producers <cough> had a talk with her, telling her it would be good for the show & ratings to keep him on. If she was pretty sure she wouldn't be picking the other guy she would have picked for instead, then what is the harm? DO WHAT'S BEST FOR THE
SHOW.
I think the producers
generally let DWTS run it's course, if no interference is needed. However, they WILL step up to do what is best for the ratings & advertizing of the show.
Exactly what I said above.

Bristol's leaving would be short term talked about (
one week,) if she left on Tues. She stays around another
several weeks, she gets talked about, Tweeted, FBed, talked about on news/tabloid/entertainment shows for
several weeks. ALL of which is in the "best interest of the SHOW."