I\'ve experienced/seen chunky in the past from a few different things.
* Prep. The metal surface of some minis is not so great, and even a well sculpted, well produced mini is going to need prep. To start getting things smoother, you can go beyond just looking for mould lines and give the overall surface a sanding or buffing. Some people use sandpaper (good to go up from a mid to fine grade prolly), fine steel wool or Dremel type buffers. I\'ve used sandpaper and
this Dremel attachment. Sometimes you also will have pinholes or cracks in the metal to file down or fill. I\'ve used tiny drops of superglue in small pinholes and then file it down after it sets. Sometimes I\'ve even smoothed parts out or filled holes with thick applications of brush primer.
* Priming. Spray primer can have issues that result in a slightly bumpy appearance on the mini, or a totally fuzzy obvious to the naked eye look. You can get dust in the primer, spray from a little too far away so specks are dry before they hit the mini, humidity causes problems, different brands work better or worse for different people and styles. I brush prime a lot to avoid this, but you can probably find tons of threads with discussions of good primers.
* Paint thinning. This is the first thing most people will jump on when a mini looks at all chunky or bumpy. If you\'re painting right out of the bottle, this may be an issue. Assuming you\'re using paints designed for miniatures (craft and artists paints have different textures/thinning requirements), you\'ll want a base coat roughly the consistency of cream, or where you can run a toothpick or brush through it on the palette and the paint fills in pretty quickly as opposed to leaving a visible streak for some time.
* Miscellaneous other things, like old paint, or bad paint batches, which happen sometimes. Also if you use paint in flip top or screw lid bottles the paint on the lid and rim can dry and flake off into the main paint and cause bumps. They\'re usually fairly big though.
I used to use a wet palette. I stir my paints with toothpicks. Sometimes I\'d scrape off fibers from the palette paper this way, so I was turning my paint chunky/fuzzy. The wet palette also did a great job of capturing the dust and animal hair that\'s all too common in my house. The unsmooth surface on this mini are part gunked up paint and part primer - http://www.coolminiornot.com/35579. There are probably other ways to gum up paint, though I\'d definitely look at the first three items before working too much about miscellaneous paint issues.