I have about 9 months of practice under my belt, and for much of that time I did not have an amp. I recently purchased a Vox Amplug. It seems crazy but I can't help but think that it has somehow helped me to become a better player.

For example there is a barre chord that I have been struggling to play cleanly. When I try to play it there's always at least a little bit of fret buzz and occasionally a dead string or two. I attribute all of this to my technique btw.

Now I'm using the amplug pretty regularly and I seem to be playing "cleaner".

Does this question make sense? I hope it does. Does anyone else feel that an amp makes you sound better, or perhaps hides your flaws?
It depends on the amp. In general kind of like differences between playing on a clean amp vs. a distorted amp, some things will sound cleaner with an amp and others will sound messier. Fret buzz for example won't be as audible, as it is sound based on vibration of the spring at the frets, while the amp only really receives vibration over the pickups. Additionally, compression from an amp (making quiet sounds louder and loud sounds quieter for more even volume) can make somewhat poorly played notes sound cleaner. On the other hand, amps will make notes you don't mean to play more noticeable and emphasize flaws in muting.

If you have fret buzz and dead notes that you don't notice as much when you play with an amp, they are probably still there and it wouldn't hurt to work on them, though you might be getting satisfactory results as far as what you hear come out of the amp.
A clean amp will allow you to hear certain flaws in your playing that can't be heard on a distorted amp, because the distorted amp tends to cover some of your flaws by distorting your sound. However, a distorted amp will allow you to hear certain flaws (mostly muting issues) that cannot be heard on a clean amp, because the distorted amp amplifies the mistakes that you normally wouldn't hear on playing on a clean amp.

With that being said, the fact that you went from playing unplugged to playing plugged also helped, because playing with any amp will make your sound louder (duh) and thus it's easier to pick out flaws that you wouldn't normally hear when playing unplugged.
Thank you for the replies. I am improving at a steady pace. I can remember when i started playing, there were many simple passages that were simply too difficult for me. Even something like the intro to "come as you are". I was having such a hard time with it that i had no concern about buzz or mutes. Now that i can find frets without looking at the fretboard (frequently) and skip strings without looking at my right hand (usually) i am finding time to worry about other stuff.