How to bulk delete posts or threads that are SPAMMy and has common phrasses in them?

One way is to use vBulletin Search function. I do it by clicking "Advanced Search" link on the forum homepage. Just get onto the Search page. Then select "Search Single Content Type" tab.

Search In: Search Type: Posts
Search for Posts: Keyword(s): here paste common phrasse that is in SPAMmy posts (in case of phrasse with spaces, add it into quote like: "this is bad phrasse")
Show Results as: Posts (or Threads if want to delete whole threads)

click "Search Now" button

You can see your SPAMmy posts, 25 per page, you can tick them all and click to delete them all.

If you want to display say 200 posts per page, paste "&pp=200" at the end of your forum URL with search results (example

vBulletin will not return more than 100 results, to change that, go to AdminCP -> Settings -> Options -> Message Searching Options and tweak "Maximum Search Results to Return" and "Search Results Posts Per Page" options

Moreover if you want to search for short words or common words like: is, your, was then add these words on same vBulelting config. page (Message Searching Options) into text field: "Words to be Included Despite Character Limit"

Dont forget revert changes made on "Message Searching Options" page to prevent high load on your server when members search.

Before doing any big deleting, backup mysql database.