Are you getting these results in actual alerts or only when you test fire the alert from Advanced Alert Manager?
Testing alerts doesn't always test against valid UnDP data. Generally, the test will send the results of the first data point it finds for the object; the real test is of the alert action (email, snmp trap, etc). If you are seeing valid data on your linear gauges, then I would guess that you are getting solid information in your polling.
You can confirm with this SQL query:
SELECT n.caption AS 'DEVICE', cpa.assignmentname AS 'UnDP', cp.rate AS 'RATE', cp.rawstatus AS 'RAW', cp.status AS 'STATUS', max(cp.datetime) AS' LAST POLLED' FROM CustomPollerAssignment cpa JOIN Nodes n ON n.NodeID = cpa.NodeID JOIN CustomPollerStatus cp ON cp.CustomPollerAssignmentID = cpa.CustomPollerAssignmentID WHERE cpa.assignmentname like 'upsAdv%' GROUP BY n.caption, cpa.assignmentname, cp.rate, cp.rawstatus, cp.status
-ZackM