Aegis, I used to feel that way too, but, recently, I have changed my mind.

A tutor who is studying another language, does know what you are  going through and how hard it is to put yourself out there and all the other challenges that a language learner faces.

But I have had many monolingual tutors, myself, who have had remarkable intuitions on what needed to be changed in my language learning approach.

 A good tutor has to have a mix of so many qualities and it is really hard to pin them all down and box them in under one label.

Teachers are language learners too generally here on italki. You give a lot of advice about language learning yourself, aegis. Sometimes even when it's uninvited. Like telling others to get over their "culture shock" and find a boyfriend/girlfriend or whatever to learn a language, what's their problem, why is it so hard for them to learn a language ... 

What's the difference between teachers and yourself? 

I sometimes tell students who are struggling to be coherent that I also make a mess when I speak Italian (which is true).  It's nice for rapport which is important, but doesn't necessarily mean that I am a better teacher in other areas.

I learnt French and Spanish many years ago to an intermediate level, and doing so helped me understand English grammar more quickly when I started as an EFL teacher.  But it seems to me that the best way to be a good EFL teacher is to train and get lots of experience.  You will eventually see the same issues time and time again, and learn new or better ways to teach them.

If you don't have a decent knowledge of other languages, I think that you would miss out on some experience of how other languages are structured differently to English.  

The other thing is that, on a forum like Italki, I think only native English-speakers would have the luxury of not having to learn a second language.

Then who do you think is qualified to give advice to other people here? You, I suppose? ㅋㅋㅋ

Teachers are in a very good position to give advice regardless of whether they have learned a language to fluency or not. They are in a good position to monitor the success of methods of teaching or learning by following the progress of the students. They can evaluate which methods work and which don't and why certain students do better than others, and based on that knowledge offer good advice. 

The advice given by people who have learned many languages I tend to take with a grain of salt these days because they don't seem to have learned those languages to depth.

Other people including teachers who have learned languages to fluency have had special circumstances afforded them that others cannot such as having studied the language major full time for years or have been exposed to native speakers at a young age. Sometimes they give wrong advice without meaning to not realizing that others would not be able to reach the same level of proficiency using their methods because they don't have the same exposure to the language that the advice giver did. 

I tend to look at the results of that teacher's teaching to check whether their advice is good or not.

When people talk about their personal experiences, good and bad, it can help others with their language learning. It can encourage others who are experiencing the same thing. Being dismissive of other people, telling them that they are to blame for the bad experiences they have had is on the other hand not helpful. Advice given in this sort of spirit where putting down others in order to try and elevate oneself is the least helpful kind of advice in my opinion. Being patronizing and boasting about how successful one has been in language learning also is off-putting behavior.