As GiantTree pointed out in his comment on the question itself: there are no viruses for Android. There's malware, though – but according to stats it's affecting less than 1% of the users (and even less than 0.15% of those using Google Play Store as their only source for apps).
I'd never trust an app calling itself "anti-virus" if just for the fact of its name (trying to sound scary and fighting what's not there). I'm using Android for 5 years now, never used any AV app – never got infected. Often the opposite is true: I've read more reports of some "AV app" misbehaving than about one being helpful. Very few are capable of heuristic scans – so all they mostly do is comparing package names with a database of known malware.
A side-effect in many cases is a "wrong security feeling": People having some "AV app" installed think it will protect them anyway, so they're getting more careless. As pointed out, those apps are not really a protection on their own (they might be useful as a component – but not as the only one in use; they are completely useless without activating the
brain.apk in your head ;) – so with those people, they rather increase the risk.
Added the number of "false alerts" outnumber those of "gotcha, bad app" – I feel no need to use one (YMMV). And those SMS you're reporting are just to "make money": someone suggesting me an Anti VIRUS app for Android makes himself suspect immediately.
The situation they describe is rarely prevented by such an app – but by using your brains when installing other apps:
- Are they real (or a fake just sounding real – e.g. playing on name similarity)?
- Aren't their requested permissions "excessive" (they should match the app's purpose – e.g. no need for a plain wallpaper to do phone calls, or a calculator to read your contacts)?
- Is the source respectable and safe (I wouldn't install any
*.apk file downloaded "from the wild", e.g. RapidShare or some Donkey exchange)?
That, plus not clicking on everything that "pops up" (ads and the like) is protecting your device much better than some strange "Anti-Placebo" app.
See also: Is an antivirus really needed for Android?