Let me ask you, do these look like creatures of pure evil?
Goblins from the movie 'Labyrinth'.
If your answer is 'no', then we're in agreement on the matter! So, why the bad reputation? For starters, often times goblins get lumped in with their larger more violent cousins, the Orcs. While it is true that goblins can come in sizes varying from the itty bitty to that of a small child, it is rare for them to grow to the same size or larger then the average human! Goblins are typically much smaller ad less malicious then their cousins and are often incredibly clever. If they are in the company of orcs it is most likely because the goblin doesn't wish to be eaten!
Goblins are known to have a fondness for ale, bread and the warmth of a fire, but what goblins seem to be the most fond of is causing mischief! A goblin in your home may 'misplace' your keys or one of your earrings, cause your milk to sour, or tease your cats so they seemingly meow angrily at nothing but thin air. While this can be very tiresome, a goblin in your home, if feeling benevolent and having been treated well can help snap you out of a lazy slump with a pinch to the rear! If you've made a particularly kindly connection with a Goblin, he is a creature with strong associations with Earth and can be helpful in magic involving this element.
As is the case with a lot of races, including we humans, a few bad apples can ruin things for everyone! While not all goblins are malicious, one should be wary of them as they would any stranger as one never quite knows if the goblin's mischief will be harmless or harmful.
P.S. Goblins in popular fantasy tend to be a lot larger and vile then their faery lore counterparts. If you're familiar with The Lord of the Rings trilogy or the movie "Legend" you'll have run across larger goblins with a penchant for evil and sometimes a taste for human flesh. In my experiences, while I adore Blix, I've yet to come across a goblin who is anything like him.
Blix from the movie 'Legend'.
P.P.S. Expect to be visited by a few wee goblins here very soon!