Are factory chain-saw blades junk or is it me?
I bought a Husqvarna 455 Rancher and I love it as a first chainsaw. I notice though, that the blade gets dull after a good amount of sawing. I purchase a file with a guide to resharpen, and have successfully sharpened it a few times. It seems to dull quicker than I would like. Do you think I am not sharpening it enough, or are factory chains junk? Thanks for answering.

Depending on the wood your cutting all chain saw blades dull fast. In an 8 hour day your going to sharpen it at least once.
It is you. Factory blades are super sharp and run great. When you resharpen them you can never get the same sharpness that it had when it was new. Close maybe. Get used to it–you have unreasonable expectations.
Usually the factory blades have anti kick back feature…If you are good with the saw and extra careful, you may want a chipper chain
you said it your self the blades get dull after a good amount of use !!!.
factory chains are 100ths of a mm accurate. its your sharpening no offence intended. maby try and add a bit more presure to the file or a littel less depending. it is hard to get it right you will try it all diffrent ways going at the blade hell for leather, a tip take the same amount off each blade so when its totally blunt they are all blunt togeather. i know this is going to sound daft but are you filing both blades?, try buying a better set of guides and a better file i know a good work man never blames his tools but it does help the job if you have got descent 1′s
The chain is fine, it"s the guy sharpening it. There is some skill involved when it comes to this.