object object

I am back on the coding trail and struggling to get this javascript working:

function QuotePotentials(QuoteName)
{
    var serverUrl = document.location.protocol + "//" + document.location.host + "/" + Xrm.Page.context.getOrgUniqueName();
    var oDataEndpointUrl = serverUrl + "/XRMServices/2011/OrganizationData.svc/";
    oDataEndpointUrl += "QuoteSet?$select=QuoteNumber,quote_details/sp_SellingProductId&$expand=quote_details&$filter=QuoteNumber eq '" + QuoteName + "'";

   //    oDataEndpointUrl += "QuoteSet?$select=quote_details/sp_SellingProductId&$expand=quote_details&$filter=QuoteNumber eq 'QUO-02084-M3Z0'";

    var service = GetRequestObject();

    if (service != null)
    {
        service.open("GET", oDataEndpointUrl, false);
        service.setRequestHeader("X-Requested-Width", "XMLHttpRequest");
        service.setRequestHeader("Accept", "application/json, text/javascript, */*");
        service.send(null);
        var requestResults = eval('(' + service.responseText + ')').d;

        alert(requestResults.results.length);

        if (requestResults != null && requestResults.results.length > 0)
        {
            var QuotePots = "";
            for (var i = 0; i < requestResults.results.length; i++)
            {
                alert(requestResults.results[i]);
                var res = requestResults.results[i];
                var resId = res.sp_SellingProductId;
                alert(resId);




                QuotePots = QuoteProdGroup(requestResults.results[i].sp_SellingProductId);                
            }
            return QuotePots;
        }
    }
    return false;
 }

The first alert tells me the number of lines returned from the quote.

The second alert says [object Object].

The third alert says undefined.

Below is the Results (JSON) I get from using the OData Query Designer when I run it.

{"d" : {"results": [
{"__metadata": {"uri": "http://aserver/XRMServices/2011/OrganizationData.svc/QuoteSet(guid'4c9e3192-eaf6-e311-ba1a-02bf0a86f1e1')", "type": "Microsoft.Crm.Sdk.Data.Services.Quote"
}, "quote_details": {"results": [
{"__metadata": {"uri": "http://aserver/XRMServices/2011/OrganizationData.svc/QuoteDetailSet(guid'3a1ea403-a268-4f93-94e9-49f89a10e600')", "type": "Microsoft.Crm.Sdk.Data.Services.QuoteDetail"
}, "sp_SellingProductId": {"__metadata": {"type": "Microsoft.Crm.Sdk.Data.Services.EntityReference"
}, "Id": "1ac1e0d9-9d8c-e211-a049-02bf0a86f1e1", "LogicalName": "product", "Name": "PPS200 c/w SLV"
}
}
]
}
}
]
}
}

I am trying to pull put the GUID for the product and then pass this to another function, but can't reference it.

Any help would be appreciated.

Matt