Spamming Tag Words Advice/Information

Farley Productions

Pursuing the Arts one step at a time.
I was recently reading a blog online about the "The Top 15 Youtubers who have had been banned" ranging from gambling on Runescape, squishing little critters with boots, to drama and the list goes on. One that caught my eye however was "Banned from spamming tag words." Which I understand is against Youtube's TOS (Terms of Service) but would anyone know of good examples and what to look out for when creating tags for your own videos?

It's simply something I'd like more insight on just to make sure I'm not someone who is spamming tag words myself. Thank you for the insight everybody. Much appreciated. =]
I'm not sure what the person did exactly, but one way of spamming tags is by placing them in the description of the video like this:

This is a video about blah, blah, blah.

-tag #1
-tag #2
-tag #3
-tag #4
-tag #5
-tag #6
-tag #7
-tag #8
-tag #9
-tag #10
Yeah, there were mainly 2 examples of what people were doing:

1) Tags in description in list form. As perfectly explained by @6StringMadMan above. ^^

2) Misleading metadata. - Here people were putting the tags in the correct place (in the tags field), but they were using tags that didn't describe their content to try and trick the algorithm. Example putting "pewdiepie" in their tags and trying to surf off his success. Or if Justin Bieber was trending in the news, people were putting "bieber" as one of their tags even though the video had nothing to do at all with Justin Bieber.
Okay, that makes more sense now that @Crown and @6StringMadMan explain it. I mainly just wanted to make sure I wasn't overusing tags or doing something wrong. But now that you've both shared a couple of examples I know that I'm doing okay. Thank you. =]