Try my new plugin See Hidden Chat. It shows the hidden chat that poison plugin's use.

This checks for OPs and Creative players that shouldn't be, and for the most commonly used poison plugins. It will be updated fairly regular, or as soon as I know what the latest poison plugin is.

Installation:

To use this plugin, download the latest version and put it in your server plugins file. After this is done, then reload/restart your server. This will then generate a config file. Open this file in your text editing software, I recommend NotePad++. Then, change the "AllowedOPs" to what accounts you would like to be allowed to have OP, if you use a permissions plugin such as group manager, you should clear this list/only have your own name and only use permissions to give people command access. This makes it near impossible for someone to get command access as the need to OP themselves and will be kicked for it.
After you have done that, you should edit the AllowedCreative list for the accounts you want to have creative. Don't worry, everytime you want to upgrade someone to creative, there is an in-game command you can use which is listed in the commands section below.
You should then change the welcome message. This is what displays when an OP or Creative player joins.
Finally, change the AutomaticCheck integer for the time, in milliseconds, between each automatic check for poison plugins, OPs and Creative players.
Once all these are set, reload/restart your server once more, and Anti Poison-Plugin is setup.

Commands:

AllowedOPs:
Description: Gives the list of allowed accounts to be OP
Permission node: APP.CheckOp
Usage: /AllowedOPs
AddOP:
Description: Adds a Player to the allowed OPs list
Permission node: APP.AddOp
Usage: /AddOP <player name>
RemoveOP:
Description: Remove a Player to the allowed OPs list
Permission node: APP.RemoveOp
Usage: /RemoveOP <player name>
AllowedCreative:
Description: Gives the list of allowed accounts to be creative
Permission node: APP.CheckCreative
Usage: /AllowedCreative
AddCreative:
Description: Adds a Player to the allowed creative list
Permission node: APP.AddCreative
Usage: /AddCreative <player name>
RemoveCreative:
Description: Remove a Player to the allowed creative list
Permission node: APP.RemoveCreative
Usage: /RemoveCreative <player name>
Check:
Description: Checks all online players if they are allowed to be OP or creative
Permission node: APP.Check
Usage: /Check
CheckPoison:
Description: Checks for known poison plugins
Permission node: APP.CheckPoison
Usage: /CheckPoison

All OPs have permission by default. There currently isn't an autoupdater, so check back every once in a while to see if there is a new update, which should at least have an update notifier.

Anti Poison-Plugin