Nope and yep, in that order. :> As long as they're texture packs. If you're using something like an x-ray MOD, something that actually changes lines of coding in your client, then if that server has plugins which are capable of detecting when you use it to completely re-render all blocks on your screen, they'll know. If they have plugins installed which are capable of detecting that sort of thing, and if it's a mod, not a texture pack.
Edit: An extremely selfish person tried keeping the account all to themselves again- why, we'll never know, since that has no positive effect on themselves. The password is now what it used to be before the last change. The seven letter one, started with "h," two words, no space.
Edit2: The pass has been changed again for similar reasons. Send me a PM for the updated account information.