It's obvious from this thread that there are a variety of thoughts on volunteers. As someone said up thread there are all sorts of ways to engage visitors.
However, there is an audience (quite a sizeable and vocal one at that) for what many on this thread find overbearing. Just after Covid many of our volunteers were shielding and nervous about coming back to volunteer (especially inside), so the room stewards/ guides were somewhat stripped back. The comment cards and emails were full of disappointment and wishes for the volunteers back. Whilst some of MN would rather not have the level of interaction there is a vocal group who love it. Certain bus tour groups love the interaction. Plenty of visitors also respond well to it and it is often fed back as hugely positive in the comment cards which is what management use to inform training and volunteer use.
On the idea of a badge scheme, I can assure you even if such a system was brought in some of the most overbearing will ignore it anyway.
No matter how much training we give, volunteers are unpaid and volunteer their time. We can train and guide but if they wish to ignore it, they will and there is little we can really do. No-one wants to say they cannot volunteer there anymore due to them been overbearing or a bit of a bore. I've been part of the training group when we acquired a military museum as part of our group. It had previously been independent and run entirely by volunteers (all old servicemen in the armed forces). The comment cards were not kind, our department was asked to investigate and help them with their tours. We first went to see what was going on. Well, tours were advertised as 40 minutes long and as an overview of certain exhibitions (aircraft, tank, a couple of notable service people related to the site, a couple of notable medals), the reality was... The shortest tour I went on for over an hour and had great detail about the engine, cockpit layout, paintwork, the preservation process and history of every aircraft. A massive tangent about some medals that were not on the advertised tour that took about 30 minutes and then saw me, looked at his watch and finished the tour. The longest tour I went on was nearly 3 hours. Again, huge detail about every aircraft, long winded tangents about everything. It became very grandpa Simpson for a time as we heard all about his war story. There was a couple of veterans in the tour group and a good hour was spend reminiscing together. Fantastic men who did incredible things for our country but tour guides they were not. I spoke to the tour groups afterwards, there were mixed reviews. The 2 veterans had a wonderful time and absolutely loved the tour. Several loved the stories. Some really loved the knowledge and the ability to answer every question. Others found it too long and a bore fest. We went daily for a month and the feedback was so mixed. The most vocal group absolutely loved it. The less vocal ones hated it and vowed never to come back. They were lovely men, who just really wanted to share their passion and tell their stories. No matter how much rejigging, guiding them and making suggestions we made, the tours were still nearly 3 hours long as it only took a question from the group or someone in the tour group to be a veteran and the tangents began.
Same was for when they were not guiding. They stood near exhibitions and were supposed to answer any questions and interact with visitors. Again, their passion and love for their subject took over, it was very much a pouncing situation. They just loved to share their stories and were very passionate that the history was not lost. No amount of some people just want to take it in/ let people come to you could deter them.