How does a recipient know they can satisfy the transaction script to spend their bitcoins?
I don't think your threat model makes sense. If you "send me Bitcoins I can't claim", you've done the equivalent of nothing at all, except you've wasted some of your own Bitcoins in the process.

Currently, clients will only recognize Bitcoins as being sent to them if they can confirm they can claim them. Non-standard transactions (those with scripts other than the two well-understood forms) are ignored.