porn-update

I would add the poptm (poptm.com) popunder on my sites, but because in the past I've had bad surprise, I want to first ask you

There are known problems of poptm? For example, it is disliked to the search engines, or after a while earnings go down drastically, etc.

poptm also provides a script in php for pop-unders, is the first time I see him, I would use, has anyone tried it? Problems?

Thanks