Dual-agency (or transactional agency... whatever your state calls it) in my opinion, is a clear conflict-of-interest.
The seller, who hired the agent, in part for his/her expertise in negotiation is deprived of that skill, since the agent can no longer advise one client over the other.
The buyer, who hire an agent, in part for his/her expertise in negotiation and experience in inspections and what to ask for in the way of repairs and credits is deprived of that knowledge because the agent can no longer advise one client over the other.
In a dual agency situation, the only one the agent is truly service is him/herself.
The listing agent would be better off having the buyer sign a waiver of "no agency"... so that you can continue to advise and counsel your seller.