Sewer smell confined to inside of toilet bowl

[Jim165]

Guys, just did a search and didn't find quite the exact same situation I'm experiencing. I get a urine/ sewer smell when I flush my rarely used 2nd bathroom toilet. However the smell is coming directly from INSIDE the bowl...not the tank, not the base where the wax ring is, nor from the sink or tub drains. Occasionally, my master bathroom toilet has the same problem. The smell does not permeate the entire house, it's restricted to the toilet bowl and, at it's worst will smell up the bathroom. I've scrubbed the entire toilet with bleach and hot water, yet the smell persists. I keep the toilets spotless at all times, so it's not a cleanliness issue.
Just a litte more info:
House is on concrete slab
Toilets do not rock, they are sturdily mounted
There is carpet in both bathrooms (yuck)
House is 8 years old.
seemingly no drainage problems, but I've just used the super-concentrated drain cleaner last night in case there are clogs in the system. I will check back today to see if there is a difference.
Otherwise, what else could be the problem? I'd really appreciate any insight!

[Cass]

Try adding about a 1/4 cup of bleach to the tank full of water, stir / mix it well and flush the toilet 1 time and let it sit for an hour then flush a few more times to rinse out the tank better.

See if that helps any.

How do you know the wax ring is not bad?

[Randyj]

My first suspicion is to question the toilets being vented properly...sewer gas coming back into toilet.....?????

[Jim165]

How do you know the wax ring is not bad?

I'm not definite that the wax ring is not bad, but if it was, I thought maybe i'd be able to smell some of the fumes at the base of the toilet. When I put my head directly into the bowl while flushing, I could distinctly determine that the smell is coming from the commode's drain (I thought it was the water at first).
It seems to intensify just before the bowl begins to fill back up. No smell from any other drains in the bathroom nor the base of the commode..

[Jim165]

My first suspicion is to question the toilets being vented properly...sewer gas coming back into toilet.....?????

Randy,
What am i looking for in terms of venting tubes, hoses, etc.? The only feed I see going to the toilet is the cold water supply line...Thanks...

[Jim165]

Try adding about a 1/4 cup of bleach to the tank full of water, stir / mix it well and flush the toilet 1 time and let it sit for an hour then flush a few more times to rinse out the tank better.

Thanks for the suggestion, Cass
I acutally tried this after I scrubbed the tank walls and bowl with bleach. I then filled the tank with boiling water to flush the entire system. After refilling the tank with cold water, I inserted a chlorine tablet. This has masked the smell a little bit, but the smell's still there...

[plumber1]

I don't think your nose is as accurate as you think it is.

Do what Cass suggests and if the odor persists, re-set the toilet.

[Cass]

The chlorine tablets don't do what a 1/4 cup of bleach in the tank will do.