Pub singalongs are different from club singarounds and different again from a folk club floor spot night, or a musicians session. There are valid arguements for each and they each have their value, but they are different. Unfortunately how people advertise and describe things does not always enable you to identify which it is until you actually get there, and even then if there is an "organiser" they might have their own ideas about what it is they expect. People often go expecting one type (often because that is what they are used to) and find it difficult to adjust when it's something different. It may also be useful to bear in mind when criticising an "organiser" that that person may have had to do a lot of behind the scenes negotiations to get the landlord to accept the idea especially when sometimes they may not have a PEL.