I don't see any problems with yum_repositories -- although you do show 'fws-testing' and 'smeupdates-testing' (so you may have something unexpected installed)
Step 1 -
The yum cache may be damaged - clean and recreate it.
(Note: smeserver-php-scl is already installed on my server, so the final 'yum install' command shows 'nothing to do')
# yum clean all
Loaded plugins: fastestmirror, post-transaction-actions, smeserver
Cleaning repos: base remi-safe smeaddons smeextras smeos smeupdates updates
Cleaning up Everything
# yum update
Loaded plugins: fastestmirror, post-transaction-actions, smeserver
Setting up Update Process
Determining fastest mirrors
 * base: repo1.ash.innoscale.net
 * smeaddons: mirror.canada.pialasse.com
 * smeextras: mirror.canada.pialasse.com
 * smeos: mirror.canada.pialasse.com
 * smeupdates: mirror.canada.pialasse.com
 * updates: repo1.ash.innoscale.net
base                                                              | 3.7 kB     00:00     
base/primary_db                                                   | 4.7 MB     00:02     
remi-safe                                                         | 3.0 kB     00:00     
remi-safe/primary_db                                              | 1.2 MB     00:02     
smeaddons                                                         | 2.9 kB     00:00     
smeaddons/primary_db                                              |  14 kB     00:00     
smeextras                                                         | 2.9 kB     00:00     
smeextras/primary_db                                              | 110 kB     00:00     
smeos                                                             | 3.1 kB     00:00     
smeos/primary_db                                                  | 1.1 MB     00:00     
smeupdates                                                        | 2.9 kB     00:00     
smeupdates/primary_db                                             | 553 kB     00:00     
updates                                                           | 3.4 kB     00:00     
updates/primary_db                                                | 6.6 MB     00:02     
No Packages marked for Update
# yum install smeserver-php-scl --enablerepo=smecontribs,epel,remi-safe
Loaded plugins: fastestmirror, post-transaction-actions, smeserver
Setting up Install Process
Loading mirror speeds from cached hostfile
 * base: repo1.ash.innoscale.net
 * epel: d2lzkl7pfhq30w.cloudfront.net
 * smeaddons: mirror.canada.pialasse.com
 * smecontribs: mirror.canada.pialasse.com
 * smeextras: mirror.canada.pialasse.com
 * smeos: mirror.canada.pialasse.com
 * smeupdates: mirror.canada.pialasse.com
 * updates: repo1.ash.innoscale.net
Package smeserver-php-scl-0.4-25.el6.sme.noarch already installed and latest version
Nothing to do
Step 2
Verify everything related to the yum config
a. According to the output you provided from db yum_repositories show, you have these repositories enabled:
# db yum_repositories print |grep status.enabled |sed 's/repository.*status/repository\tstatus/'
base=repository	status|enabled
remi-safe=repository	status|enabled
smeaddons=repository	status|enabled
smeextras=repository	status|enabled
smeos=repository	status|enabled
smeupdates=repository	status|enabled
updates=repository	status|enabled
Run # yum repolist to make sure that the remi-safe settings from yum_repositories have been correctly added to /etc/yum.smerepos.d/sme-base.repo.  
(If 'yum repolist' does not include 'remi-safe' on your system, run 'expand-template etc/yum.smerepos.d/sme-base.repo')
# yum repolist
Loaded plugins: fastestmirror, post-transaction-actions, smeserver
Loading mirror speeds from cached hostfile
 * base: mirror.cogentco.com
 * smeaddons: mirror.canada.pialasse.com
 * smeextras: mirror.canada.pialasse.com
 * smeos: mirror.canada.pialasse.com
 * smeupdates: mirror.canada.pialasse.com
 * updates: mirror.cogentco.com
repo id                             repo name                                     status
base                                CentOS - os                                   6,710+3
remi-safe                           Remi - safe                                     2,856
smeaddons                           SME Server - addons                                28
smeextras                           SME Server - extras                               165
smeos                               SME Server - os                                   905
smeupdates                          SME Server - updates                              150
updates                             CentOS - updates                                636+1
repolist: 11,450
b. If you see any unexpected repositories in the output of yum repolist, find out where they come from
- Make sure that "reposdir" points only to /etc/yum.smerepos.d in /etc/yum.conf
# grep reposdir /etc/yum.conf
reposdir=/etc/yum.smerepos.d
- Confirm that the only file in /etc/yum.smerepos.d is sme-base.repo (the file that gets built from the yum_repositories db):
# find /etc/yum.smerepos.d/ 
/etc/yum.smerepos.d/
/etc/yum.smerepos.d/sme-base.repo
Step 3
See if you have any extra or unexpected packages installed
This command will list any packages installed from any repository not currently enabled:
# yum list extras
This command will list any packages that are not included in a base SME server installation:
# /sbin/e-smith/audittools/newrpms