I know Dave will shoot me for this, but I also imagine that your particular antenna does not radiate efficiently enough to see huge gains from much of the mobile tricks to reduce noise and increase efficiency. I am not saying they can't make contacts, just that no one should expect it to perform awesomely, especially on the receive end.
The popular ones tend to be the Hamstick®, and the various copycats. All are very low in efficiency, as their Qs are about 50 or less. A few of the 80 meter models have Qs less than 10! If you want a really lossy antenna, use one of the stubby 3 foot long versions!
Their only attributes are, light weight, low wind loading (some models), and low cost (≈$20USD, less mount). This means they can be attached by just about any type of mount, some of which add to their overall losses (i.e.: license plate mount). Efficiencies range in the .3% to 20% (80 through 10 meters), and they typically don't need matching as the system losses bring the input impedance to near 50 ohms.