...So, the vocal booth I have is slightly sexy, cozy, and perfect... 
...The end result may be non-sexy...
...So the Op should only concentrate on his room echoes, outside sounds, a possible closet, fiberglass base-traps, and/or 'sexy' quilts...
...with materials from Walmart and Lowes (based on our posts) ... a sexy one at that. 
...($40 for a huge sexy one)... 
...Now, someone might chime in and utterly ridicule our crudely sexy vocal booths; just ignore them.

Ok - clearly there's a problem here. 

I don't mean this as the aforementioned ridicule, but I feel that something must be said here.

I couldn't help but notice this peculiar over-the-top obsession with the word 'sexy' used way too often here and completely out of context.

Whenever I see someone use the word 'sexy' to describe inanimate objects, recording gear, or anything else, [which I've seen way too often], it automatically makes me picture a 14 year old male-fem-boy sneaking onto his Mom's computer & posting when she's not looking.

Now I'm sure that's not the case here, but...that's just what image automatically comes to mind - no offense intended by any means whatsoever, so please don't take any. I don't know you, we've never met, we have no personal history, so I'm not aiming at you personally at all, and again mean no offense.  

Instead, just consider the request below, [as this is really starting to get to me & apparently others, IIRC]:
 
In all cases, as with this one, the OPs' only planning to record with it, mix with it or sing into it, not f**k it!

So, [and with all due respect], do us a favor & PLEASE stop using the term 'sexy' to describe things that you're not planning to f**k!

Thank you.