niko-tina:
The thing is: there is a rule that disallows subject dropping BUT it is not strictly applied.

There is a rule, but not in sense of "you do that and no way for other". There is a rule produced by practical usage. It means roughly: "It's commonly impossible imply subject since it creates confusion (but still grammatically correct). If there is no confusion it's ok."

niko-tina:
As I always say, the important thing is the communication. When saying something, one has to make the receiver understand WHAT you are saying, and not HOW (unless intended to). I hate when people stares at me paying attention at my accent. Even though they're trying to be nice, they don't get what I'm talking about. That's why I try to make myself as clear as possible, and the same should apply here.

I'm absolutely with you. Implying a subject (in some cases) will not counter it. As i said again, it's widely used in very-very obvious cases: imperative mood and answering to ĉu-question.

Rogir:

Would saying "Uma!" or "Tiel ruĝa!" when seeing said fire truck be correct?

When you are a three-year old, yes.

It was an honest question! If someone was a Red-ophobe, they might just scream "Tiel ruĝa! TIEL RUĜA!" over and over again and high tail it out of there. It's not all that contrived...

Rogir:

Would saying "Uma!" or "Tiel ruĝa!" when seeing said fire truck be correct?

When you are a three-year old, yes.

That's a European-biased subjective opinion. There is no law in Esperanto that says that saying a single word is wrong or indicative of age (although, saying "red" when one sees a firetruck is indeed mature, but more because we assume that everyone knows firetrucks are red).

Anyway, there is a danger, people, when we go and teach people that one method is correct and tell them to not use a particular construction which is related but not as used. What will happen when they actually encounter it? Quite frankly, if international use of Esperanto results in these kind of large discussions which meaninglessly go around in circles, then Esperanto is clearly being used inefficiently. A learner of Esperanto needs to know how to interpret different grammatical structures, writing styles, and uses of the language which are divergent from the mainstream or of doubtful correctness. If the flexibilities of Esperanto can't be taught, then we might as well not bother with it over other conlangs. Lingua Franca Nova is just as easy to write and easier to pronounce. What gives EO the upperhand over those conlangs like that is the flexibility of the grammar, verbs, word order and tenses, granted by the unique classification system of EO (word endings) and by the fundamento.

I think that everyone understands that they might see more different grammatical forms in actual spoken Esperanto than they will see in their Esperanto course. In many languages there is a big difference between what is taught in the classroom and what is spoken on the street, but in the case of Esperanto, I can honestly say that this is not the case. Our writing is much closer to our colloquial speech than is the case for most languages. very few differences, and nothing I can think of off-hand that would cause anyone a problem.

There have been quite a lot of proposed changes to Esperanto, since it is a created language, and since some people see that as license to "fix" it. And yes, a beginner can be expected to encounter someone who talks using some crazy modification to the language, every now and then. It's not widespread enough to cause problems to someone who learned in a standard course. And it's a very helpful community, so it's never a problem to say, hey, what does that mean?

So ceigered, I understand your concerns, but I don't see it as a real problem in the case of Esperanto. As far as forms that you haven't specifically been taught, all you have to do is ask, hey, what did you mean by that? Even I do it on occasion, if someone uses a word I've never heard before. Esperanto is a second language for almost everyone who speaks it, so these kinds of questions are very welcome.

For reference, lernu takes great pains to ensure that the material in its courses is grammatically correct. The course texts are written in standard Esperanto. The lessons given in the form of conversations are written in standard conversational style. Those are grammatically correct, but also written to reflect what natural Esperanto conversation sounds like.

OK, points taken

(Also, don't get me wrong, I wasn't trying to fix or change Esperanto, just trying to discuss what I saw as a potential danger in the way it's taught, but you addressed that in the last two paragraphs so all is good for now - or maybe that cat nap I had did me good )