Hi @helxsz
Maybe it is not as obvious as it could be, but the libraries you see in the web-based IDE are in fact user-contributed libraries not provided by the Spark team. Most of the libraries are really high-quality ports from similar Arduino libraries but sometimes people have differing setups or goals so results can differ. Lots of folks have had good results with @mtnscott 's library for these DHT parts.
As @jerome has rightly pointed out, the DHT series of sensors are somewhat on the low-end of what you can get today.