Sort of... where HK's really can be hope killers is when a weather waiver is issued and revenue pax can change their flights at no charge. Recent non-rev experience of mine was a boatload of HK's suddenly appearing on a flights that were otherwise wide-open the morning before. They were pax changing to earlier flights to beat the weather, and were HK because no seat assignment until at the gate. In that sense they are "standby" in that they are awating seat assigment, but they do show in the seat count after (and only after) they execute their flight change. Our hope was killed (there were 3+ flights with 40+ open seats just 24 hours prior) and we ultimately had to get a hotel and brave the weather the next day.