The overwhelming majority of PLR is crap (not to mention the original stuff...but that's another story). So even if you get spectacular graphics, copy, etc. for your PLR, it'll still be crap. The copy might sell a lot of it, but many of your customers will not be happy at having been duped.

Ok, so you may have rewritten the PLR a bit. It doesn't change the fact that you're probably not providing any value to your customers. If you're selling the PLR as a standalone product, then your customers will likely not get any value out of it unless they're a total newbie (I'm just talking IM PLR here). If you're selling PLR as part of a business-in-a-box type deal, well...most BIAB vendors just make their money without telling folks how to profit with their BIABs.

To answer your question, it wouldn't be impossible to do a launch. However, you're not going to impress any JV partners with your PLR (unless it's really good and you've got some JVs who owe you for promoting their stuff). You could certainly do an internal launch. It's just a little tricky to do because of the lack of good PLR out there ("good" meaning the type of PLR that you wouldn't need to change too much before putting it back on the market).

On a related note, you must have an original product that belongs to you (or someone you're working with) to get a slot on JVNP's premium mailings.

I would personally never launch a reworked PLR product. I wouldn't want to discourage anyone from doing it though...I'd just tell them to have their customers' best interests in mind while doing it.