checking wget's return value [if]

Others have correctly posted that you can use $? to get the most recent exit code:

wget_output=$(wget -q "$URL")
if [ $? -ne 0 ]; then
    ...

This lets you capture both the stdout and the exit code. If you don't actually care what it prints, you can just test it directly:

if wget -q "$URL"; then
    ...

And if you want to suppress the output:

if wget -q "$URL" > /dev/null; then
    ...

$r is the text output of wget (which you've captured with backticks). To access the return code, use the $? variable.

$r is empty, and therefore your condition becomes if [ -ne 0 ] and it seems as if -ne is used as a unary operator. Try this instead:

wget -q www.someurl.com
if [ $? -ne 0 ]
  ...

EDIT As Andrew explained before me, backticks return standard output, while $? returns the exit code of the last operation.