This is a bit of a complex subject and I should warn that not even local solicitors are likely to give you a full and correct answer.
1) As far as I know planning applications for entire developments (urbanizações) of the type you are describing would not have been required to have been declared whether they were to be used for tourism use when constructed.
I live in Lagos in a similar property and as far as I know from the escritura there were no restrictions on the full development being used for tourism rentals.
Several units on our block are rented out and it can be uncomfortable between 15th July and end of August but that is the price we pay for a great sea view.
2) As regards individual properties these do require licenses.
The law was introduced in the late 90's but not applied by many councils. A year or two ago several Camara's realised they needed new revenue streams and started applying the law. The result is that many people have taken their properties of the "official" rental market.
Have a look at this link which may explain things a bit more clearly.
http://www.expatfocus.com/index.php?name=Forums&file=viewtopic&t=17890
However, as far as I know the law does not cover things such as noise pollution.
Your only hope might be to check with the Camara to see if the properties in question have "Licença de Alojamento Local" and if not stir things up that way.
Alternatively, you might try raising the issue with the German Rental Agency.
I would point out that this is not restricted to just German tourists.
British, Irish and Dutch Tourists have a similiar reputation at this end of the Algarve.
