Disagree. I've taken apart HVAC units in budget to luxury chains--these use the cheapest air filters, and often show years of dirt/grime from lack of replacement.

We carry a Winix HEPA filter on trips and have done so since Nov 2020, paid $99 at costco. It fits in a roller duffel bag that just meets carry-on size limits.

When we operate it a few feet from the hotel room door, the air quality light goes to amber or red for a few minutes when the door is opened, then quickly returns to green . We have also used this into a family home during a visit, and into a restaurant when we had a private room reserved.

//note to others: don't plug a 110V US appliance into an overseas 220V power outlet. Stupid mistake. Now I am shopping for a replacement