Some painters used to make a mixture of very cheap flat wall paint plus drywall mud, and roll that on as a one step texture/paint finish. Sometimes the stuff would be troweled, other times not. The problem is that it gives a porous finish, and subsequent coats may soften it an cause it to peel. Old wallpaper paste is the enemy of anything really adhering to your walls at this point.
If you're fixing up to sell, maybe the quick & dirty will suffice. Other than that, a real skim coat is the only way to go, after either removing or blocking the paste residue.
Casey

Benjamin Moore makes an underbody primer intended to smooth out slight imperfections. If you'd rather have texture, though, Behr & Insul-X make texture paints that you can find at your local hardware or home improvement store. A cheaper option would be watering down joint compound (drywall mud) and rolling or troweling it on to your desired texture, then priming over it before painting (once the mud has dried), but you may have trouble getting these options to match existing texture.

Thanks for the answers! I was planning to get a gallon of Gardz and use that first as a primer and to neutralize any glue that might have remained. The wall currently has no texture so maybe the thinned drywall mud would work well. How watered down should the mud be - I assume paint consistency?.

I have also seen these spray cans of texture and perhaps that would work also. We don't want thick texture at all, just a light surface texture so the walls don't look slick. In fact, I wonder if the nap from the roller would provide enough "texture". That would make things easy.

Spray cans are great (though smelly if you can't get the latex-base), but they can add up in price if it's a large wall. Maybe it's worth it to you for your desired result with a non-intimidating solution, though. And yes, paint on a roller does have a slight texture. I painted my completely smooth bathroom walls with even a low nap roller (1/4") and there's a *very* slight texture to the walls. Using a thicker nap, like 3/8", would leave a little more of this subtle texture. Going too thick, though, could start to cause problems with running & spattering.