When you make an offer directly with the listing agent, the agent will disclose the possible working relationships that exist – whether they are going to represent both you and the seller, or just represent the seller. There will be a document you sign called an “agency disclosure” that spells out the relationship.
When representing both sides, an ethical agent becomes more of a transaction facilitator or perhaps a “dual” agent, depending on what state you are in. In effect, they are not an actual advocate of either party but mostly an information provider and communication conduit.
The agent will convey offers and counter-offers back and forth, but won’t provide opinions to one party or the other on how “negotiable” the other party might be. In addition, they will answer questions, explain things such as the transaction progresses, make suggestions about whether getting inspections is a good idea – and so on – but they won’t be your advocate or the advocate of the seller.
If the agent discloses that they are acting just for the seller, then they are the advocate of the seller — and you are on your own.