When swapping with BOB members should we try to keep the trades pretty even? example: Like not trade 3 kids paperback books for 3 trade-size paperbacks or HC. If this happens should I decline or let the other person know I think it's an unfair swap? If I let them know how do I word it to not sound rude? Or is this just the way BOBs works?...a book is a book, there are no unfair trades?

If I start a BOB swap & want a HC book, should I offer to trade 2 PB's to make it an even trade...shipping $ wise?

I have done this before.  I had someone make a BOB offer for a thick tradesize book.  I pm'd and politely asked for 2 mmps for it and she said no problem.  The tradesize I had, had 2 stories in it so really it worked out the same for her. I don't know if I would ask on a regular one story tradesize or hardback since if I sent it out on a regular request I would only get one credit for it anyway. But it doesn't hurt to ask. IF they so no just be polite about it.  

I have also asked for 2 books when someone has made a BOB offer on an audio book from me. Bobs can be negioated however you want.  Just be polite and don't be afraid to say no and don't get upset if they decline your suggestion. 

I've done a few BOBs so far and never really thought about that. We just traded x number of books for x number of books and most were mixed between paperback and hardcover. Interesting thought though. I guess it would just depend on the circumstances of that particular swap!

The vast majority of my BOB swaps have been equal insofar as 3 books for 3 books, 5 books for 5 books, etc., regardless of book size, age range.  I once requested 5 MMPBs from someone, who asked if they could have 10 smaller children's books, and I was fine with that.  Just recently I requested 1 MMPB from someone, and since they picked a large HC, they offered me a 2nd PB.  When it comes to romances, I've had people ask for an extra or offer me an extra since they're small as well.  So my advice is to do what feels right to you.  If you don't want to swap out your MMPB for a childrens' book, then don't, or ask the other boxer if you can add an additional book.

I just finished a swap where a very small book was requested from me. The only thing I found on the boxer's shelf that I wanted was a large HB coffee table book. I PM'd and offered her another paperback because I felt it was not fair. She had no problem with the one for one trade, but I included another book she said she had not read anyway.

can you say I can include x book but not x because ....?

Most BOBs I've done have been even 3 books for 3 books type.  I have had one where the other person had lots of kids books & offered to do 2 kids books for one of mine to make it more even in postage, but as my kids have a huge bookshelf already I went with the books for me.  As for PB vs HC -I'd trade those evenly.  I don't even pay attention anyway to if a book is PB or HC, I'll read it either way ;)

I did have a BOB recently where I ordered an audio book not realizing it (like I said I don't pay much attention to bindings & in BOB it doesn't have the red '2 credits' note on audios) & the sender was fine swaping me evenly for one book but I felt guilty when I opened the box so I sent her the next book in the series she had ordered from me.  It wasn't necessary, she even said so, but I felt it was only fair.

can you say I can include x book but not x because ....?

As in an offer comes in for 2 books, book A & book B, you can send book B but not A for whatever reason?  You just take book A out of the offer & give the requestor time to decline/approve.  I've had this happen where 2 people send me offers the same day, both included the same one book & both had books on their shelves I was interested in.  I removed the duplicate request from the 2nd offer & sent them a PM letting them know about the other offer that came in 1st & I thought it only fair to let the 1st offer stand for now.  The 2nd person checked out my shelf & picked a different book for the box & both BOB's went through.