ugly color for directories in gnome- terminal?

The answer to your question is hidden in the answers to both What do the different colors mean in the terminal? and How do I change the color for directories with ls in the console?

The cause of the green highlighting is because your directories are writable by other (o+w) and not sticky.

So that explains why they have green highlighting, but you also ask how to remove it. You say "make it look like the others", by which I assume you mean normal directories. Open up your ~/.bashrc and append the following to the bottom:

export LS_COLORS="$LS_COLORS:ow=1;34:tw=1;34:"

save the file and then run

source ~/.bashrc

Now they will look the same as any other directory. Take note though that the system thinks this is information you should be able to see, by doing this you will no longer be able to see it easily. Consider choosing a different background color from the list here. I think purple isn't too bad (ow=1;34;45:)

Explanation:

ow stands for 'other, writable', tw is 'sticky, writable' (the other condition that has a green background). I found these values by examining the contents of $LS_COLORS on my system, looking for values with a background color of 42 (green). The color code has 3 columns (unused columns are left out):

bold;font-color;bg-color

This is because you have given write permission to other, meaning other than file owner and not in the group. Check permissions with ls -l or ll. Remove write permission from other by chmod 0755 directory_name, so it will look similar to other directories.