The Sporeggar reputation is a very small reputation thats located in western Zangarmarsh. The Sporeggar reputation can be raised one of two ways. One, by collecting the Sanguine Hibiscus's from Underbog and the other by doing the "Now That We're Friends" quest. The Sanguine Hibiscus is my personal favorite method.
If you're level 80 you'll easily be able to dodge any mobs in Underbog, which will allow you to collect the Hibiscus's almost un harmed. However if you'd like to do the quest instead, that is also an option. Below is a quick run down of the quest.
You'll accept the quest in Sporeggar. Once you have it in hand fly northeast to the Naga's by Marshlight Lake. Here you'll want to kill 12 Bloodscale Slavedrivers and 6 Bloodscale Enchantress's. This quest gives you 750 reputation and can be done fairly quickly.
If you'd like to watch a video of me farming the Sanguine Hibiscus's in Underbog click here.