I recently bought a new Acer Aspire E15 Start laptop.
Windows 8.1 (no choice) and bought new (from Argos).
I was aware that there would be 'clutter' included, but I spent the first couple of days 'fighting' unwanted downloads - not made easy because of my unfamiliarity' with W8 - and an inability to spot/find the necessary commands amongst the stupid W8 interface.
I eventually found how to download my preferred browser (Firefox) and thence suitable (to me) anti-spyware utlities which enabled me to locate and identify the unwanted programmes that crept in.
That some were akin to Trojans is certain.
Some kept producing adverts for unwanted services (and further undesirable 'apps') that the unwitting would simply accept as possibly 'essential'.