Ew. Ew. Ew. Stop - No don't put spackle over wall paper - Oh too late is it?
Ok lets look at the options:
1. Complete removal down to the dry wall.
First of all this is going to be a lot of work unless you are blessed and have a semigloss paint beneath the wallpaper and one of the "newer" wall papers which have a water based glue. Then all you really need is to peel the dry survace layer of wall paper (usualy a water resistant coating like vinyl) and a spray bottle with warm water (warm water because lets face it who wants to play with cold wet paper?) Spray the paper and let stand a few minutes - it will loosen the glue and the paper will peel off rather easily - in a relative way.
If you are unlucky the wall paper was put over a flat or even unpainted surface, That means that no matter how delicate you are you may end up pulling what ever wall texture is beneath, be it smooth plaster or spray texture. Worse yet there may be several layers of wall paper in that case renting a steamer is the better option since you can steam through the layers. You can get a good guess-ament on the wall treatment if there is a connecting hallway that is just painted. Usually people tend to paint flat over flat, semigloss over semigloss. Few rare birds will paint semi-gloss over flat becausethey know that a semigloss cleans up easier than a flat paint.
2. Filling, sanding, retexturing over wall paper. All in all a "bad idea" but it can be done and obviously it has been done. But, for the same reasons you point out, it isn't done due to the uneven surface features. Unless you have plastered dry wall before and know how to use the tools to even out seams you may find the job to be too complex and unsatisfactory.
That is if you want a smooth surface. If you opt for a rough textured appearance you will be using that roughness to hide the flaws in the wall. In fact most modern houses are textured not because it looks pretty but because the construction company can spend less time fine tuning the plaster job by covering any flaws and unevenness with a sprayed and knocked down texture. Underneath many "popcorn" ceilings one finds drywall, tape and a rough coat of plster over the tape and screw/nail heads.
You could use a regular wall plaster, a trowel and large putty knife and a spounge, or rag or newspaper or just about anything. Spread out a thin layer of plaster and "pounce" your spounge, rag - what ever. This will rough up the surface lifting up peaks like on frosting. Then depending on your final look you can either wait a minute or so until the plaster starts to stiffen and "knock down" the peaks with a flat trowel by running it over the peaks to flaten them but not toatally, leaving a "texture" or you can wait until it is fully dry and hit it with sand paper. Sanding is dusty, imperfet and tends to lead to more application of material due to the clumping of plaster on the sand paper which leaves behind gouges.
3. Faux Finish: In this scenerio you select say three colors of wall paint. Say dark brown, tan and dessert sand. You paint the wall a solid dark borwn, then you use a rag, spounge - what ever to pounce on the lighter colors blending them to make a mottled finish. This will detract from the lines and visually remove them though they will still be there.
For ideas and to get a good look at those:
http://interiordec.about.com/od/spongingtechnique/ lists several sites that deal with that subject. Down side is that you might end up causing the lines to show even more if paint gets trapped along those lines.
4. Another idea is to cover with more paper and paint. No, not hanging wall paper not in the traditional sense. Take craft paper (Come in rolls, its usually brown and cheap) Rip up the paper into various sizes, say between 6"x6" to 24"x24", crumble, then apply with a wall paper past, smoothing the pieces roughly - the idea is to leave the wrinkles and to over lap the edges. The final product is a rough surface which is a "texture" then yo can paint it any color you want. My living room is done like that. When I first put the paper up it was grey (I got grey craft paper) During the remodel we painted it bright white.
http://www.hesterdecorating.com/portfolio_interior25.htm Is the same thing except they finsihed with a spounge treatment.
In any case the bubbled place will need to be fixed.
If you are removing the paper - no problem. I fyou are going to recover with more plaster, then cut away the bubble. If you are going to faux finish, I would slit the bubble, get one of those ink injection needles fill it with glue and fill the buble with glue then press the paper back onto the wall - If you are just going to cover with more ripped paper, cut off the bubble and take care to over lap edges and get a wrinkle over the area to hide the flaw.
I hope some of this helps.
Cheers
