I would never base my decision on syntax semantics and style. Despite popular belief, it's a poor formula in which to guage any aspect of anything other than skills that only reflect rote memory. By the way, stuides indicate that holers of rote memory have at best average intellegence. But the definition of average intellegence makes the point moot. The point is that it's proven that there is a large portion of people whom don't fit spell check's mole who operate on a high intellectual level.
For instance, one of the more clever sales pitches is to appear less intellegent than the customer. In a bargining setting, no one wished to confront someone of whom has a higher intellegence level. Anytime a buyer belives s/he is more intellegent than the seller, the buyer perceives an advantage over the seller.
The more clever folks who recognise the spell check mentality harness the situation. A sure fire way to give the customer the intellectual advantage would be to make a sign that says "For Sale by Oner."
My issue with engine and cars on eBay is that I would be more than cautious about buying anything, regardless to the writing style. It doesn't matter how the ad is written. The little fly-by-night freebees notwithstanding, most newspapers--at least the paper in my area--won't accept seller written advertisments. The reason is that they want a uniform writing style. (If you try to submit something such as the car for sale, it reflects on the paper. Not that newspapers do a satisfactory job, even with junior high school grammer rules, but would you buy a newspaper with something such as car-for-sale published in it?)
I would be a little more concerned with carefully crafted written discourse; simply, the more carefully crafted, the greater possibility hiding the truth. Don't they cover this in school, something called persusavie writing, or are different geners something that's only covered in high-level college writing courses?
And I would feel just as confidant with the car being sold by the poorly worded seller. In fact, in a crap's shoot, you would probabaly stand a better chance with the poorly worded ad as with properly worded. (Obviously there are no professional automechanics on this board. Otherwise, this lack of writing skills wouldn't be the factor on which to judge products.)
The bottom line is that regardless to how the ad was written, I wouldn't buy an engine at a rebuilt price unless it came from a reliable rebuilder. And I wouldn't buy a car without looking at it, regardless to how it was worded. Even so, I wouldn't rule out a look at the car based on the seller's writing ability.