Are Are wrong ratings criminal offence?

Product reviews play a very important role for buyers when making decisions. That's why companies try to put their products in a positive light.

But what happens when manufacturers or dealers write positive reviews? 
As long as the customer cannot recognize that the rating has been manipulated by the company, so-called fake valuation, or the reviewer got a discount, this is unfair competition. Furthermore, the publication of the rating is considered misleading advertising.

The situation is similar to negative ratings by competitors. 
If a competitor lets write poor ratings of competing products, it is a competitive push. No false claims should be made that could potentially damage the competitor's business.

Basically, you can say:
1) Objective criticism is permitted
as long as it is expressed as an opinion and is not directed solely at disparaging, defaming and damaging the reputation of the product being evaluated.

2) Slander criticism is forbidden, 
since the limit of what is permissible is exceeded when it is no longer a matter of dispute, but of defamation and disparagement in the foreground.

3) wrong or untrue product reviews are always inadmissible
Lügen sind keine Meinungsäußerung und damit rechtswidrig. Sie können immer entfernt werden. Im Gegensatz dazu liegt eine Tatsachenbehauptung vor, wenn Fakten genannt werden, die sich überprüfen lassen. Stimmen die Angaben in der Bewertung nicht mit der Wirklichkeit überein, kann man dagegen vorgehen.