Your wish is my command!
Back when I first started out I had absolutely NO IDEA what I was doing. At the time we were in a 3 bay shop converted gas station very small, 1500 sqft which is still not insanely small for my area. The rent was high at $3800 and I we were not doing so well financially so I decided to rent out a bay. The bay was actually an addition to the building and it had its own motorized gate. I put an ad out on craigslist and found someone to rent the space for $1600 a month.
At the time we were only working on BMWs and this person told us he specialized in Nissans, Mitsubitshi and he worked on some BMWs. We had a discussion about how since we only worked on BMWs that as long as there is no interference with our work and customers there shouldn't be any problems. Amongst many many many other things I had to deal with between this tenant and I, the major problem was that people would confuse out shop with his. BMWs would pull up and by the time their vehicle was on his lift I would walk outside look at the car, look at the customer and shake my head. The customer would then do a double take and realize he went to the wrong place!! I had discussions, arguments, etc with my tenant and he didn't seem to understand what he was doing wrong. I'll never forget what he said, "I am not going to turn away a paying customer."
In 3 years he ended up going with long bouts of no business, getting physically assaulted by one of his customers and generally sat around for months with no work. He was also 1-2 months late on his rent due to his lack of business and the best decision I made was to not give him any advanced notice when I finally left my old location otherwise he would have ditched me on even more rent.
Moral of the story is DON'T EFFING DO IT!