[SOLVED] Do people often make mistakes with gender of nouns?

And English was influenced by the French too (Normans), that's why there are often two different words in English for close concepts (calf / veal, etc ; in that case there has been a specialization later).

As far as I know, the word doctoresse is very old-fashioned. It’s apparently more widespread in Switzerland. The common feminine equivalent for docteur is either une docteur, une docteure (the one I use) or un docteur.

Another example of the fact that grammatical genders have nothing to do with sexes.

Imagine if you knew how we usually call the "penis"...

Basically that. There was also some confusion, on the hands of writers, in using the neutral, so when Latin evolved, it fell in disuse. Some (most) neutrals became masculine, others became feminine because they wound up ending in -o/-a (their declinations also changed and this termination was understood to be a mark of gender).

There are certain endings that tend to be masculine (-age, -ège, -isme, consonants in general, -eur if it is a physical object) or feminine (-ion, -son, -té, -tié, e with th expection of -age, -ège and -isme, -eur if it is a abstract noun). So le sein, le vagin, le féminisme, le maquillage etc. do follow that rule even though we think that they should be feminine.

Of course that doesn't always work. Some words end in accented letters or vowels other than e, and some go against the rules. Le problème, for example, is masculine and la mer is feminine. But I'm going through a flashcard deck of the 20,000 most common French nouns besides that once I don't know, I'm also drilling ones where I'm unsure of their gender (using un and une because you never learn if a word starting with a vowel is masculine or feminine otherwise). I noticed that more nouns seem to follow the rules than not and a lot that don't are very common like façon, main, bonheur or fois, so I already heard them so many times that I know it's la fois and le bonheur just as I know that two and two is four or what the letter "C" looks like. Though I'm sure that a lot of uncommon ones don't follow the rules either, but if it's less common than the 20,000 most common nouns, I probably don't need to have it memorized because even French people would rarely use words less common than this.

French spelling must be a nightmare for non natives. Especially our devilish mute "e" or these "s" ans "c" that don't produce the same sound depending on the following vowel or the preposterous number of different ways to write the same sound

Heard about that. It's basically like your example of "oiseau" but it happens way more often. In French it might get hard to write a word correctly only by listening to it, but once you have the written text, you can pretty much guess how it is pronounced. In Tibetan, if you don't know a word, you can't guess neither how it's pronounced nor how it's written.

english is worse than french in pronounciation, i.e Worcester

Don't get me started on the English spelling system or its phonology... it is a nightmare. In Europe, English speaking children are the one who need the most time to master reading and writing. No surprise. Even young French speakers have it easier apparently.

Concerning Tibetan and its writing/spelling system, here is a very interesting video according to which Tibetan may have the most difficult spelling system: https://www.youtube.com/watch?v=btn0-Vce5ug

Le mousse (ship's boy) # la mousse (foam)
Le voile (veil) # la voile (sail)
Le moule (mould) # la moule (mussel)
Le mode (mode, method) # la mode (fashion)
Le crêpe (crêpe) # la crêpe (pancake)
Le manche (handle) # la manche (sleeve)... (or : la Manche, the Channel)

This was an old joke about W.W.2 : in the restaurants, the French servants obligingly used to help the German officers with their coat, saying :
- Voulez-vous que je vous aide à passer la manche ?
(May I help you slipping your sleeve on? or : crossing the Channel)
(This is very likely a legend).

@Aiona: could you pls explain why german should be a mixture of english and french in Your examples? IMO ist french different and english and german follow the same principles.

I always felt dubious when hearing people explaining that French is the clearest and most logical language in the world

I thought over the question about "le # la conscience", and I came to the conclusion that the only reasonable possibility was that the speaker actually said ''l'inconscience" (unconsciousness), and not "la conscience"...

Saying that any human language is the clearest and most logical is very dubious simply because it makes no sense. I suppose you could say that of a constructed language such as Esperanto that was designed without irregularity.
I’ve never heard that said about French though, rather that it was ‘the most difficult’, but here again, it’s rather stupod to say.

Natives of all languages make mistakes; mistakes are things that are different from the usually arbitrary rules edicted by some scholars. French spelling is even worse than that, it’s what I call intellectual masturbation.

To get back to le conscience, I say again that it is possible that a native says that by mistakes (one is tired, doesn’t focus on what one says, etc.) and then corrects him/herself, or not because it isn’t a big deal. The speakers and the people listening know it’s a mistake and let it slide.

I suppose "mix" was just a manner of speaking. I don't suppose German syntax borrowed anything from Latin.
But it's not automatically a matter of declensions either.

For instance Russian possessive pronouns are a rather strange mix.
The 3rd person (his, her) agrees only with the possessor. The plural (their) is invariable. The neutral form is identical to the masculine, so there is no difference between "its" and "his". One could say it's very similar to English, even simpler.
Other persons (my, your... including a "his/her own" used when the possessor is also the subject of the sentence) do agree with the thing possessed though. Similar to German, only with 7 cases instead of 4 and an extra "reflexive" pronoun.

There were declinations in Old English, rather similar to German. Nowadays there are only faint remains of it : the possessive case, for example (John's book), or the different forms of "who" (whom, whose).