Transformers are primarily marketed at children with some figures and media aimed firmly at adult collectors but there are elements, from the creation of characters to manufacturing to storytelling that really aren't too wholesome. Here's a look at some things that are a little bit on the unpleasant side.
Bumblebee has always been our way into the Transformers universe: the character is the smallest, weakest and most affable of characters which makes him easiest for children to identify with. Most adult collectors aren't big fans of the character for those weaknesses and it seems writers aren't either as the poor little guy has been riddled with blasters, been destroyed on at least 3 occasions, had his face crushed and had to walk with a cane for a while. In nature we know that the weakest of the pack is the one singled out by predators and Bumblebee is the Transformers equivalent. However it's worth noting that there is something else darker about Bumblebee.
While we think of Volkswagon Beetles as being cute cars (mainly thanks to the Herbie films), it was actually the brainchild of Adolf Hitler. With Germany's new autobahns (motorways/highways) in place Hitler wanted an affordable car available to the people so they could enjoy their new high speed travelling option. Adolf would approach Ferdinand Porsche about creating his Volks Wagen (People's Car) with strict instructions that it should be able to sustain a relatively high speed, have low fuel consumption, have easily replaceable parts to keep repair costs down and be able to seat 2 adults and 3 children. Volkswagens were to be available to the German public via a payment scheme to help people afford them.
With the outbreak of World War 2 the Volkswagen was instead used as a military vehicle (don't laugh) because it's air cooled engine made it perfect for use by the Afrika Corps and a variation was used as an amphibious vehicle. During the war the Beetle design was a status symbol driven by high ranking Nazi officers but post war Volkswagen made vehicles for the British army and finally started producing Beetles for the German public in 1945. By 1972 the Type 1 Beetle was the most produced car in the world and immediately recognisable, thanks in part to the Disney film The Love Bug, a film about a sentient Volkswagen Beetle. The Volkswagen had finally lived up to it's People's Car moniker and the loveable car was a perfect choice for the loveable Bumblebee despite it's dark past.