As you correctly observed, English is tricky and there aren’t too many hard rules with the language, which is aggravating for English learners but also highlights its flexibility, which is an important quality for the de facto language of science, aviation, international trade, etc. So to answer the question, I think there are multiple aspects which make a combined word more likely, including: 1) the constituent words are different parts-of-speech being combined into a new part-of-speech, 2) a contraction whose spelling happens to be very similar to an existing word but is still mostly unambiguous, and 3) how likely the combined word appears in colloquial or subject-matter specific speech and writing.

Even a combo word that meets all three of those points is not guaranteed to be universally accepted as a new word, but some combo words get accepted even if they don’t meet most of those points. Starting with your examples, “greenhouse” certainly meets point #1, since “green” is an adjective and “house” is a noun, which combined form the new noun “greenhouse”. “login” does the same, although it also meets point #2, since it’s a contraction of “log in” (v.), meaning to sign into a web service. The same goes for “work out” (v) and workout (n, an exercise program for each day of week).

I personally always write “log in” when I mean the verb, and “login” (n.) to refer to the credentials needed to sign in. But that’s my CS degree showing. As such, I’m of the opinion that “login” as a verb is a typo, since it’s the wrong part-of-speech (a noun when a verb is needed). Same goes for “alot” (IMO, a typo) and “allot” (v, to allocate). Whether such typos are permissible depends on the quality of the writing, as “takecare” and “ofcourse” would be unacceptable in a dissertation but perfectly fine for an IRC chatroom for die-hard fans of British cooking shows. But I think most people in the latter group, if asked, would probably agree that “ofcourse” is a typo. Basic English literacy means we’re not going to hapazardly throwawaythewhitespace andtryto pretendthatitdoesnt matter.

Finally, prevalence, which is considered by many linguists to be the ultimate test of neologisms: if people use it and it’s understood, then it’s a word. But that rule needs to be viewed from the lens of the intended audience. For example, years and years ago, I understood the legal term “housecar” in the California Vehicle Code to mean something akin to a family saloon car, meaning a car suitable for transporting a whole family or household. This would contrast with a pick-up trucks, sports cars, and commercial vehicles. But my naivete was to not look up the actual definition, and I just wrongly assumed that definition because it made sense for “house” and “car” to combine in that way. The real definition is a car that is also a house, meaning an RV or motorhome. That just goes to show that – since I’m not a lawyer – I was not the audience to gauge whether “housecar” is a valid combo word or not. Whereas California-based lawyers would have likely recognized the meaning in short order.

Basically, each combo word is unique in its circumstances, but perhaps those three points I mentioned have a lot (haha) to do with whether a combo word achieves universal adoption. “alot” does not seem to have met the full acceptance test.

Can you be more precise about what level of automation these trucks should have? Other forms of transport like trains and aircraft have automation, but it’s not full automation and they accept that limitation as the technology develops.

SAE has a classification system for automation of the driving task, but this wouldn’t necessarily include the task of loading and unloading cargo, nor the paperwork management for consignments, all of which are part of the commercial truck driving job.

Answering the question as written and without any particular comment on the example given, yes, it can be manipulative to respond to allegations with a counter that the allegations are slanderous, but it’s not always manipulative. Though it does highlight the gap between what someone says and what they mean.

Some folks will argue that the term “slander” has lost its original meaning but I still ascribe to the legal definition which says it’s a form of defamation. That is, a falsehood being perpetuated about someone, regarding something that can be proved one way or another. Without defining the term, no one could sensibly answer the question here.

So does this mean when person X asserts slander, they’re saying they have a potential lawsuit? Possibly, but that’s the rub: “slander” is now colloquial shorthand for “all those things they said about me are lies” rather than “I now have cause to sue”. It’s natural to refute unsavory descriptions about oneself, even in spite of attached evidence, so sometimes calling something as slanderous is a knee-jerk reaction, akin to saying “ow!” after stubbing one’s toe on the bed post.

But that’s the most charitable view. “Slander” can also be a rejection of the validity of the evidence, and that’s more a symptom of the “post-truth” era we’re currently in, where controversies are more newsworthy than the truth they purport to stand upon. In that sense, labeling allegations as slanderous is manipulative because it serves the purpose of misleading the audience, or encouraging them to not bother vetting or even looking at the evidence at all. And sometimes you can’t blame the audience: fact checking is difficult and boring.

I bemoan the use of legal terms in colloquial speech, as terms of law must be exact and precise, while colloquialisms must be free to express broad thoughts and ideas. But since laypeople are rarely asked to consider if a comment is actually legally actionable, and most off-the-cuff commentary isn’t, I won’t dwell on that aspect.

Sometimes it’s the original allegations which are genuinely manipulative, and it’s not manipulative to point out manipulation. Other times, no possible reading of the facts can save the remaining reputation of a genuinely awful person.

But what I will say is that a simple response of “it’s slander!” alone is not persuasive, IMO. If someone wants to be believed, they’ll have to put more effort into their defense than that, insofar as public perception is concerned. But if the evidence is bad, this shouldn’t be very hard to do.

The public and media might also bear some responsibility, if they will so easily equate “both sides” as having valid points when there’s an avalanche of evidence on one side and only bad evidence on the other. But other times, a factual question can be reasonably interpreted differently, and that’s fair too.

So I’m sorry to say that there’s no clear cut answer, whether it’s always or never manipulative. I’m not a lawyer, but their common adage is “it depends”.