You conveniently ignored the "No" answer to your question about public photographs taken in your summary here.
It might not surprise you, given that you cannot just be photographed out in public against your will (assuming none of the mentioned exceptions apply), that the right to your own picture is not impeded by whose property you are on when that picture is taken or what the relationship of the person taking the picture to the property owner is. The right to your picture is yours, whether you stand on the public street or stepped 20cm onto someone's driveway.
Consent is assumed when you are made aware of photos being taken and you enter the property anyway. For example a supermarket with a big "we videotape you in here" sign on the entrance. However, it is also assumed that those pictures are taken for a valid purpose, will not be used for other purposes and will be deleted after no longer being necessary for the purpose. In case of the supermarket it is assumed you consented to being videotaped for the purpose of theft prevention and security, at least that is what all the signs said that I ever saw. You never consented to having excerpts of your clumsiness being shown on youtube as "stupidest customers this month". That would be illegal use, even though they have a right to take your picture for their original purpose.
So this is about being informed about it prior to taking pictures and the assumed consent for the stated purpose by affirmative action of going ahead and letting the picture be taken instead of turning around and not entering the property.
That said, the property owner explicitely lying to you, there can be no consent, not even assumed consent or any grey area. Taking pictures of you while you are not aware of it has no legal basis.
While I doubt the Police will come and arrest anybody, if people snapped a picture of you at a party, that you don't want them to have, legally, they'd have to delete it.
There are many specific laws at play here when you consider severe cases (person drunk, naked, on the toilet, underage etc) but for lighter cases (person just did not want to be photographed) it is included in the general laws about personal rights. You can read all about it for example here: https://de.wikipedia.org/wiki/Recht_am_eigenen_Bild_(Deutschland)