During my many conversations with restaurant, pub and hotel owners I can tell you this:
Brittish and German customers are very welcome, good spenders. They demand quality and are sensitive for personnal attention instead of mass tourism.
The Japanese tour groups stay over in hotels more expensive than average. During the day they spend very little, just some souvenirs. But the Japanese expats from Düsseldorf appreciate very much the high quality of real Japanese food at Tanuki.
The Chinese stay in cheaper hotels,all tour groups, all costs included. They raid the morning breakfast, plastic bagg in the hand for the midday lunch. Not even 1 beer in the hotel bar at night.
The Brittish bring also many 1 day holiday shoppers by coaches, from even the Midlands . They buy some chocolates, some have a lunch, but at 16h00 they all start to walk back to the coach parking. On the way back , they will stop at a tabacoo and beer/liquor store.
French and Dutch tourists are a mix of cheap day tourists as well as people who stay over, visit a museum, watch a special concert, go for an expensive meal. They come by car or train.
Sometimes we see Italian and Spanish school groups ( arriving by coach ) , who stay mostly at the youth hostel outside the city center for 1 night. They are good customers of the hamburger restaurant at the central market square

and some local pubs. And that is it.
A special group are the Belgians themselves. Arriving by car, coach or train, it is a very mixed lot. The impact of the Bongo cheque is quite important. Some higher class hotel owners complained to me that it brings them customers who received such a "weekend in Bruges" from the family or friends for early retirement or a jubilee. But those people hardly know how to behave in a hotel. And they complain that they have to pay for things that are not included in the Bongo ticket. Well.
1 group I have not mentioned: people who arrive by airplane. They do exist because the coaches from Charleroi ( Ryanair and Wizzair ) come to Bruges. Not from Zaventem

Where is the study that proves that those tourists coming by LCC bring us any benefit - if not chase away other tourists?