I've only ever done liens in TX and PA, so this may not help. I tried it once in CA and got burned because I was wet behind the ears. Both states had vastly different processes, but legally there was one common thing. The person who is owed money must be the one to initiate the lien. Of course, you could be a little untruthful and do something like a storage lien and claim it was on your property for the requisite time, but the current title-holder could cause all kinds of trouble if you are the one initiating the lien. If he/she contests it and comes forward with the something like "I took it to a repair shop on [insert date] and abandoned it, so this can't be true." In PA, if I file a lien for something like storage, I have to prove that a verbal or written contract was enacted. All it would take is one affidavit from the title holder saying it isn't true and I would be in a heap of trouble. I could be charged with vehicle theft and go to jail. In TX, I did a dozen or so liens at the repair shop; abandoned vehicles, unpaid bills, etc. We had pretty ironclad proof; receipts, paystubs to the mechanic, dated and signed documents, etc. You as an individual wouldn't have that unless you more or less forged it.
In the two states where I did a mechanic's lien, I was issued a title in my name. The shop should have a title once the lien is released. If they don't, then your state does it differently, or you're being lied to and about to recieve a stolen vehicle.
In TX, a repair lien was something like an $80 fee. We would give supporting documents to a guy at the local tax office and he would file the lien. 30-60 days later, we would have a clean title for the vehicle. The only time I did it in PA, it was supremely old-school; place a classified ad in the legal section of a periodical, certified snail-mail to the last three owners on record, waiting period, etc.
But in all of the cases, it wasn't that the system couldn't be easily massaged, it's that getting caught massaging the system was heavily punished. I would never purchase a vehicle without a title unless it's something like a race car or parts vehicle. I would make the shop do the lien, get the title, and do it all above-board.
The CA one I tried turned out OK (by that I mean I wasn't charged with auto theft and put in jail), but wholly unsuccessful. A guy I worked with rented a storage unit for his contracting business. He sublet the associated parking space to a guy who wanted to store his 911SC. 911 owner disappeared and stopped paying, so my buddy filed a lien and gave the car to me. I was told that the title was coming and it never did. I filed for a title as an abandoned car after it had sat in my driveway for the requisite 30 days. The DMV of course contacted the title-holder and within a few days he showed up with police accusing me of stealing it. After I explained what had happened, they went after my "buddy" who gave me the car instead of pursuing me. Not sure what happened to him, but long story short, he never applied for the storage lien so the car was reported stolen by the owner.
TL;DR... do it properly. Don't massage the law.