People judge a company as more sustainable when it adds eco-friendly products than when it removes unnecessary ones, even when the additions create more waste. That is the finding of a study published in the Journal of the Academy of Marketing Science, which calls the pattern the sustainable additive bias. Researchers from the University of Bath and five other business schools and universities ran nine studies covering hotels, consumer products, conferences, festivals and trade shows.

What Happened in the Hotel Rooms

Researchers ran the field test in April 2025 at a four-star hotel in a European city, with 302 guests staying a single night. Some rooms got a larger set of eco-friendly amenities, including organic or biodegradable toiletries and reusable items. Others got a pared-down set with refillable dispensers, limited paper goods and extras available on request at reception. A third group kept the hotel's standard amenities.

Guests in the rooms with more green items rated the hotel most sustainable, scoring it 5.05 against 4.63 for the pared-down rooms and 4.30 for the standard ones. The pared-down and standard rooms did not differ significantly. The fuller rooms also drew the best overall experience scores. They produced the most waste as well. Housekeeping weighed what was left each day, and waste came to 55.1% of the weight of items offered in those rooms, compared with 52.9% in standard rooms and 51.1% in the pared-down ones.

Why Removal Goes Unnoticed

Perceived corporate environmental effort explains the bias, the researchers found. An added green item looks like an investment, while a missing one leaves guests nothing to notice. The effect flipped for conventional products, since adding ordinary items lowered sustainability judgments. Lead author Diletta Acuti of the University of Bath summed it up in the university's announcement by noting that additions are visible and removals are not.

Procurement teams redesigning amenity programs, event materials or customer gifts face two separate decisions. Switching an item to recycled or biodegradable material settles what it is made of. Whether guests need it at all is a separate call. Chains that have cut single-use plastics have already made removals of this kind, the type of change the study suggests guests are slow to credit.

Making Less Visible

The authors suggest companies explain the environmental reason for removing items and keep a recognizable cue, such as a refillable dispenser, so a smaller offering still reads as a sustainability choice. Their tests found that a strong, familiar cue weakened the bias. Anti-greenwashing rules on environmental claims apply to that message as much as to any other.

All of the hotel results come from one property in one city, and waste was measured as a share of items offered, not across each product's life cycle. Companies already treating waste as a strategic resource have the measuring habits to test a leaner offer. Purchasing volumes, reception requests and waste weights before and after the change would show whether the savings in this one hotel carry over to their own properties.